The spring sky

1/05/2015| Galactic whirlpools from Richard Pearson on Vimeo.

Running time: 40m
Made with the help of the BBC

We begin with a tour of the spring sky followed by a look at galaxies.

The Whirlpool galaxy, like others of its kind, contains thousands of millions of stars, and it is impossible to doubt that many of these stars must be attended by inhabited planets. There must be astronomers, too, living in the midst of Messier 51 and using telescopes, and they will be able to see our Galaxy as a faint, blurred spiral of light in their sky.

October 2014 | Active weather systems

1/10/ 2014 | The Outer Planets from Richard Pearson on Vimeo.

I would like to thank professor Kunio Sayanagi & Trevor Barry for all their help while making this program. We do not often hear about the outer planets, now is a good time because there is interesting things happening in the weather systems of the planets Saturn & Uranus which is causing excitement among planetary astronomers. In addition, the planet Neptune was at opposition on 1 September 2014 and Uranus will be at opposition on 7 October. A planet is at opposition when it lies opposite to the Sun in the sky, and is therefore best placed for observation.

Here is a link to The William Herschel Museum web site | http://herschelmuseum.org.uk/

September 2014 | Comets Unveiled

Comets are colourful fuzz-balls in space that have a small rocky nucleus, a shimmering hallo of dust known as the coma, and a long dusty tail stretching thousands of miles in length. They have been seen by sky watchers for centuries, and were once believed to be omens to bad fortune.

Over the last decade, a number of spacecraft have visited comets, and have helped to reveal their secrets, in this month's program we look at some of their findings to help better understand the discoveries that await us from Rosetta over the next year.

Please visit our web site Vimeo where you can watch all the past shows of Astronomy & Space, and If you like this program please share it with your friends, and members of your local astronomical society.

A Spectacular Landscape of Star Formation

This image, captured by the Wide Field Imager at ESO’s La Silla Observatory in Chile, shows two dramatic star formation regions in the southern Milky Way. The first is of these, on the left, is dominated by the star cluster NGC 3603, located 20 000 light-years away, in the Carina–Sagittarius spiral arm of the Milky Way galaxy. The second object, on the right, is a collection of glowing gas clouds known as NGC 3576 that lies only about half as far from Earth.
          NGC 3603 is a very bright star cluster and is famed for having the highest concentration of massive stars that have been discovered in our galaxy so far. At the centre lies a Wolf–Rayet multiple star system, known as HD 97950. Wolf–Rayet stars are at an advanced stage of stellar evolution, and start off with around 20 times the mass of the Sun. But, despite this large mass, Wolf–Rayet stars shed a considerable amount of their matter due to intense stellar winds, which blast the star’s surface material off into space at several million kilometres per hour, a crash diet of cosmic proportions.
          NGC 3603 is in an area of very active star formation. Stars are born in dark and dusty regions of space, largely hidden from view. But as the very young stars gradually start to shine and clear away their surrounding cocoons of material they become visible and create glowing clouds in the surrounding material, known as HII regions. HII regions shine because of the interaction of ultraviolet radiation given off by the brilliant hot young stars with the hydrogen gas clouds. HII regions can measure several hundred light-years in diameter, and the one surrounding NGC 3603 has the distinction of being the most massive in our galaxy.
The cluster was first observed by John Herschel on 14 March 1834 during his three-year expedition to systematically survey the southern skies from near Cape Town. He described it as a remarkable object and thought that it might be a globular star cluster. Future studies showed that it is not an old globular, but a young open cluster, one of the richest known.
          NGC 3576, on the right of the image, also lies in the Carina–Sagittarius spiral arm of the Milky Way. But it is located only about 9000 light-years from Earth — much closer than NGC 3603, but appearing next to it in the sky.
NGC 3576 is notable for two huge curved objects resembling the curled horns of a ram. These odd filaments are the result of stellar winds from the hot, young stars within the central regions of the nebula, which have blown the dust and gas outwards across a hundred light-years. Two dark silhouetted areas known as Bok globules are also visible in this vast complex of nebulae. These black clouds near the top of the nebula also offer potential sites for the future formation of new stars.
          NGC 3576 was also discovered by John Herschel in 1834, making it a particularly productive and visually rewarding year for the English astronomer.

Scientists spot white dwarf reigniting and exploding

It is a blaze of glory rarely seen in the universe.

Astronomers have proved for the first time that dead stars known as white dwarfs can reignite and explode as supernovae.

These incredible images were created to show the stages of the spectacular death,The finding came after the unique signature of gamma rays from the radioactive elements created in one of these explosions was captured for the first time.

Astronomers using ESA's Integral gamma-ray observatory now say they have demonstrated beyond doubt that dead stars known as white dwarfs can reignite and explode as supernovae. 

The 'smoking gun' in this case was evidence for radioactive nuclei being created by fusion during the thermonuclear explosion of the white dwarf star, the European Space agency said.

'Integral has all the capabilities to detect the signature of this fusion, but we had to wait for more than ten years for a once-in-a-lifetime opportunity to catch a nearby supernova,' says Eugene Churazov, from the Space Research Institute (IKI) in Moscow, Russia and the Max Planck Institute for Astrophysics,in Garching, Germany.

Although Type IA supernovae are expected to occur frequently across the Universe they are rare occurrences in any one galaxy, with typical rates of one every few hundred years.

Integral's chance came on 21 January 2014, when students at the University College London's teaching observatory at Mill Hill, UK detected a type IA supernova, later named SN2014J, in the nearby galaxy M82.

According to the theory of such explosions, the carbon and oxygen found in a white dwarf should be fused into radioactive nickel during the explosion.

This nickel should then quickly decay into radioactive cobalt, which would itself subsequently decay, on a somewhat longer timescale, into stable iron. Because of its proximity – at a distance of about 11.5 million light-years from Earth, SN2014J is the closest of its type to be detected in decades – Integral stood a good chance of seeing the gamma rays produced by the decay.

Within one week of the initial discovery, an observing plan to use Integral had been drawn-up and approved.

Using Integral to study the aftermath of the supernova explosion, scientists looked for the signature of cobalt decay – and they found it, in exactly the quantities that the models predicted.

'The consistency of the spectra, obtained by Integral 50 days after the explosion, with that expected from cobalt decay in the expanding debris of the white dwarf was excellent,' says Churazov, who is lead author of a paper describing this study and reported in the journal Nature.

With that confirmation in hand, other astronomers could begin to look into the details of the process. In particular, how the white dwarf is detonated in the first place.

25 Years Ago, Voyager 2 Captures Images of Neptune

NASA's Voyager 2 spacecraft gave humanity its first glimpse of Neptune and its moon Triton in the summer of 1989. This picture of Neptune was produced from the last whole planet images taken through the green and orange filters on the Voyager 2 narrow angle camera. The images were taken on Aug. 20, 1989, at a range of 4.4 million miles from the planet, 4 days and 20 hours before closest approach on Aug. 25. The picture shows the Great Dark Spot and its companion bright smudge; on the west limb the fast moving bright feature called "Scooter" and the little dark spot are visible. These clouds were seen to persist for as long as Voyager's cameras could resolve them. North of these, a bright cloud band similar to the south polar streak may be seen.

In the summer of 2015, another NASA mission to the farthest zone of the solar system, New Horizons, will make a historic first close-up study of Pluto. Although a fast flyby, New Horizons' Pluto encounter on July 14, 2015, will not be a replay of Voyager but more of a sequel and a reboot, with a new and more technologically advanced spacecraft and, more importantly, a new cast of characters. Those characters are Pluto and its family of five known moons, all of which will be seen up close for the first time next summer.

Image Credit: NASA

A Needle in the sky

This stunning new image from the NASA/ESA Hubble Space Telescope shows part of the sky in the constellation of Canes Venatici (The Hunting Dogs). Released 21/08/2014 2:21 pm. Copyright NASA & ESA (Acknowledgement: Roelof de Jong).

Magnitude: +10.4 | Surface brightness: 14.00 | Dimension: 15.9’ x 1.8 ' | Position angle: 48 | Coordinates: Apparent RA: 12h18m 16.4s DE:+37°42' 43"

Spiral galaxy NGC 4244, nicknamed the Silver Needle Galaxy spans some 65 000 light-years and lies around 13.5 million light-years away. It appears as a wafer-thin streak across the sky, with its loosely wound spiral arms hidden from view as we observe the galaxy side on. It is part of a group of galaxies known as the M94 Group.
Numerous bright clumps of gas can be seen scattered across its length, along with dark dust lanes surrounding the galaxy’s core. NGC 4244 also has a bright star cluster at its centre. Although we can make out the galaxy’s bright central region and star-spattered arms, we cannot see any more intricate structure due to the galaxy’s position; from Earth, we see it stretched out as a flattened streak across the sky.
A number of different observations were pieced together to form this mosaic, and gaps in Hubble’s coverage have been filled in using ground-based data. The Hubble observations were taken as part of the GHOSTS survey, which is scanning nearby galaxies to explore how they and their stars formed to get a more complete view of the history of the Universe.

This stunning new image from the NASA/ESA Hubble Space Telescope shows part of the sky in the constellation of Canes Venatici (The Hunting Dogs).

Although this region of the sky is not home to any stellar heavyweights, being mostly filled with stars of average brightness, it does contain five Messier objects and numerous intriguing galaxies — including NGC 5195, a small barred spiral galaxy considered to be one of the most beautiful galaxies visible, and its nearby interacting partner the Whirlpool Galaxy (heic0506a). The quirky Sunflower Galaxy is another notable galaxy in this constellation, and is one of the largest and brightest edge-on galaxies in our skies.

Joining this host of characters is spiral galaxy NGC 4244, nicknamed the Silver Needle Galaxy, shown here in a new image from Hubble. This galaxy spans some 65 000 light-years and lies around 13.5 million light-years away. It appears as a wafer-thin streak across the sky, with its loosely wound spiral arms hidden from view as we observe the galaxy side on. It is part of a group of galaxies known as the M94 Group.

Numerous bright clumps of gas can be seen scattered across its length, along with dark dust lanes surrounding the galaxy’s core. NGC 4244 also has a bright star cluster at its centre. Although we can make out the galaxy’s bright central region and star-spattered arms, we cannot see any more intricate structure due to the galaxy’s position; from Earth, we see it stretched out as a flattened streak across the sky.

A number of different observations were pieced together to form this mosaic, and gaps in Hubble’s coverage have been filled in using ground-based data. The Hubble observations were taken as part of the GHOSTS survey, which is scanning nearby galaxies to explore how they and their stars formed to get a more complete view of the history of the Universe.

Jupiter’s magnetic field revealed

Max Planck researchers penetrate with computer simulations deep into the interior of the giant planet Jupiter.
Superlatives are the hallmark of the planet Jupiter. Thus, the magnetic field of the largest member is about ten times stronger... than that on Earth, and it is in the solar system at the cloud top by far the most extensive magnetosphere around a planet. Puzzling it seemed a long time that this field has a similar structure as that of our planet, although both celestial bodies in the interior are constructed entirely differently. A team under the leadership of the Max Planck Institute for Solar System Research in Göttingen have now succeeded with the most detailed computer simulations to explain the origin of the magnetic field deep within the gas giant.

'We're ALL aliens' claims Scientist

By Jonathan O'Callaghan for MailOnline

Scientists have controversially claimed that life on Earth originated in space after plankton were found on the exterior of the ISS.

Earlier this week cosmonauts announced they had found the microorganisms living on one of the windows of the Russian segment of the space station.

And while the exact origin of these critters is still unknown, it has been claimed they may have come from outer space - supposedly like life on Earth.

Experiments have previously shown bacteria can survive outside our planet, but this is thought to be the first time more complex life has been found this far out in space.

Their exact origin is not yet known and will require further study - although it may just be contamination from the American segment of the ISS.

At the time of the discovery Russian experts said the tiny organisms were carried to the station on air currents from the sea where plankton is found in abundance.

However others claim this is impossible, with another explanation being that the minute plants drifted onto the ISS from elsewhere in space.

They insist this supports theories that plankton - one of the earliest forms of life - must have originally fallen to earth from space billions of years ago. And say this is proof that we are all of extra-terrestrial origin, a theory known as panspermia.

Professor Chandra Wickramasinghe, of the Buckingham Centre for Astrobiology, said algae-like organisms, or diatoms, have previously been found on meteorites which have fallen to Earth.

'Diatoms have been found on meteorites in Sri Lanka, but there has been no proof where they actually came from,' he said.

'This is the first time that we have evidence that points towards complex living organisms falling from the skies to Earth.

'The space station is orbiting the earth in a total vacuum, there is no air, so it is a total defiance of the laws of physics to say these organisms were blown into space from Earth.

'The only explanation is that they have come from elsewhere in space, and this supports long-held theories that plankton, and therefore all life on Earth including humans, originated from organisms in space.

'Everything that we have on the Earth is derived from space, including humans.'

NASA's RXTE Satellite Decodes the Rhythm of Unusual Black Hole

The signals have helped astronomers identify an unusual midsize black hole called M82 X-1, which is the brightest X-ray source in a galaxy known as Messier 82. Most black holes formed by dying stars are modestly-sized, measuring up to around 25 times the mass of our sun. And most large galaxies harbor monster, or supermassive, black holes that contain tens of thousands of times more mass.

“Between the two extremes of stellar and supermassive black holes, it's a real desert, with only about half a dozen objects whose inferred masses place them in the middle ground," said Tod Strohmayer, an astrophysicist at NASA's Goddard Space Flight Centre in Greenbelt, Maryland.

Astronomers from Goddard and the University of Maryland, College Park (UMCP) have suspected M82 X-1 of being midsize for at least a decade, but compelling evidence excluding it from being a stellar black hole proved elusive.

"For reasons that are very hard to understand, these objects have resisted standard measurement techniques," said Richard Mushotzky, a professor of astronomy at UMCP.

By going over past RXTE observations, the astronomers found specific changes in brightness that helped them determine M82 X-1 measures around 400 solar masses.

The Realm of Comets

Hello and welcome to Astronomy & Space. In this program we take a look at the highlights of the August night sky.The maximum of the Perseid meteor shower takes place on the night of August 11th which are associated with comet Swift-Tuttle, and comet ISON looks like it will be a great sight in the December night sky. Our main theme is therefore the Realm of Comets.

Thank You,
Richard Pearson

The next episode of the Sky at Night will be Next Sunday 23:50 on BBC One except Scotland, Scotland HD

It's a golden era of exploration on Mars, with Nasa's space rover Curiosity finding out new and exciting things about the planet and which might offer the best chance of life elsewhere in our solar system.

The spacecraft Mars Express is also celebrating a decade at the red planet and Chris Lintott and Lucie Green pick out some of the highlights, including the 'face of Mars'.

Meanwhile Jon Culshaw explores the Moore Moon Marathon with astronomers in Chipping Norton.

Curiosity Mars Rover Gleams in View from Orbiter

NASA's Mars Science Laboratory rover Curiosity appears as a bluish dot near the lower right corner of this enhanced-colour view from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. The rover's tracks are visible extending from the landing site, "Bradbury Landing," in the left half of the scene. Two bright, relatively blue spots surrounded by darker patches are where the Mars Science Laboratory spacecraft's landing jets cleared away reddish surface dust at the landing site. North is toward the top. For scale, the two parallel lines of the wheel tracks are about 10 feet (3 meters) apart.

HiRISE shot this image on June 27, 2013, when Curiosity was at an outcrop called "Shaler" in the "Glenelg" area of Gale Crater. Subsequently the rover drove away from Glenelg toward the southwest.

When HiRISE captured this view, the Mars Reconnaissance Orbiter was rolled for an eastward-looking angle rather than straight downward. The afternoon sun illuminated the scene from the western sky, so the lighting was nearly behind the camera. Specifically, the angle from sun to orbiter to rover was just 5.47 degrees. This geometry hides shadows and reveals subtle colour variations.

The image is one product from HiRISE observation ESP_032436_1755. Other image products from this observation are available at http://uahirise.org/ESP_032436_1755.

HiRISE is one of six instruments on NASA's Mars Reconnaissance Orbiter. The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter and Mars Science Laboratory projects for NASA's Science Mission Directorate, Washington.

Imperial College London plans ‘Mission to Mars’

Scientists have designed a concept mission to land astronauts on Mars.

The plan envisages a three-person crew journeying to Mars aboard a small two-part craft.

The craft would rotate to generate artificial gravity and use a heat shield to protect itself against solar flares.

The crew would then return to Martian orbit in a pre-sent craft fuelled using ice from beneath the planet's surface.

The concept, developed in conjunction with the BBC, is intended to spark further debate about the technical obstacles and risks that would have to be overcome in order to put humans on Mars.

Mars ‘A Dynamic World’

© BBC TV

First broadcast in 1972

Sir Patrick Moore – 5th April 2012

Astronomy & Space | Comet Ison

Hello and welcome to Astronomy & Space. In our next program on July 31st we take a look at the highlights of the August Night Sky and the Perseid meteor shower.Our main theme is Comets, what are they and where do they come from.We also have the latest news and photographs of Comet S1 2012 ISON which is scheduled to reach magnitude –4.9 on 28th November.

On Sep. 21, 2012 Vitali Nevski (Belarus) and Artyom Novichonok (Russia) discovered an asteroidal object of magnitude 18.5 in images taken with the 0.4m telescope of the International Scientific Optical Network (ISON). Although they suspected a comet, due to its motion, they did not mention anything in their discovery report. Thus, after the object appeared on the NEOCP page, other observers first noted and reported the cometary nature. In consequence the comet was given the project's name. Comet C/2012 S1 (ISON) displayed a 9" coma and a faint tail in p.a. 280°. The central condensation seemed elongated. Shortly thereafter the comet was identified on images taken on Dec. 28, 2011 and Jan. 28, 2012, which allowed the quick determination of accurate orbital parameters. Accordingly this comet will come extremely close to the Sun on Nov. 28, 2013 (0.012 AU). Since the discovery brightness indicates an intrinsically bright object, the comet could become very spectacular (CBET 3238). Assuming an average brightness evolution (n=4) the comet should reach magnitude -10 at perihelion, with the visual tail stretching about 40-50° during the following days. After perihelion the comet will move strictly northward, thereby approaching Earth. It will come within 0.43 AU of our planet on Dec. 27, when it could still be as bright as 4 mag, with a coma the size of the Moon. On Jan. 7/8, 2014 it will pass the northern celestial pole at a distance of only 3°. In case it should be a new comet (n=3), the predicted values are -5 mag / 8° / 6 mag / 7.5 mag

Gaia ‘Star chaser’

© Richard Pearson

In this week’s program our main theme is the Milky Way.

In recent news it is now estimated that there are 60 billion stars with extra solar planets in our Milky Way, and there are 100 billion stars in our galaxy. In this week’s program we highlight the European Space Agency’s new mission GAIA which is to launch soon atop of a Russian rocket to study the stars of our Milky Way in extra fine detail. 

Please feel free share this video on face book & Twitter, and among yours friends. In our next program we will take a look at the highlights of the August night sky.

Kind regards | Richard Pearson

February 12 1965 - Balloon Astronomy

In this era of rocket probes and artificial satellites, it may seem a retrograde step to turn back to the humble balloon. Yet as an astronomical vehicle, the balloon has much to recommend it, and it seemed well worth while to devote a programme to balloon astronomy in general.

To an astronomer, the Earth's atmosphere is a source of conti­nual annoyance. It is dirty and unsteady, so that images of celes­tial bodies are always to some extent blurred; to take really long- exposure photographs, of say, the surface of Mars is pointless, since the fine detail will not be registered. From this point of view the Solar System observer is in worse case than the astro­physicist, who is concerned with what are to all intents and pur­poses point sources of light; no star, apart from the Sun, shows a measurable disk even in the largest telescope yet built. However, there are more serious troubles to be faced. The atmosphere is not transparent to radiations of all wavelengths; in a large part of the electromagnetic spectrum it is depressingly opaque, so that astronomical information obtainable at ground-based observa­tories is very incomplete. From this point of view, the practice of setting up large telescopes on high mountains is of little help, though it does improve the clarity of the optical images.

The atmosphere of our world is quite extensive, and traces of it linger on up to at least 2,000 miles above sea-level, but its density falls off rapidly with height. More than 90 per cent of the total air-mass lies below thirteen miles, and more than 99 per cent of the mass below twenty miles; the upper reaches are very tenuous indeed. Unfortunately, the chief blocking-out of radia­tions is due to layers in the ionosphere, that part of the atmosphere which begins at an altitude of forty miles or so. The so-called D. E, Fi and F2 layers range up to more than 100 miles; these are regions where free electrons are found in great numbers, making ±.e levels electrically conducting (and, incidentally, making I ring-range radio communication possible, by bouncing wireless raves of certain frequencies back to earth). The layers are pro­duced by X-rays and ultra-violet rays from the Sun, which act : n the thin air; the X- and many ultra-violet rays are themselves absorbed in the process, so that they do not penetrate to the ground.

Lower down comes the ozone layer, which absorbs most of the remaining solar ultra-violet. If, therefore, we are to study these important radiations, we must send our recording instruments up to great altitudes.

Of course, rockets and artificial satellites can go far above the ionosphere, and even escape from the Earth. Yet they are com­plex and expensive, and in their present stage of development they cannot lift massive telescopes, keep them steady while the :observations are being carried out, and then return them safely. Balloons are much easier to handle, and are also vastly cheaper. Their main limitation is that they are incapable of rising to the ionosphere. A height of between 80,000 and 90,000 feet is as much as can reasonably be expected, and so balloon-borne instruments can contribute little to either ultra-violet astronomy :r X-ray astronomy. All the same, the balloon has much to be said in its favour, since it can at least carry heavy equipment above most of the atmospheric mass - thus eliminating blurring and unsteadiness of the images. Moreover, water-vapour and carbon dioxide in the lower air absorb most of the infra-red radiations sent to us from the planets. Balloon ascents overcome mis hazard with ease.

Hot-air balloons date back to the year 1783, and within a few months of the first flight a French scientist, Charles, went up two miles in a free balloon. Yet there is little resemblance between mese crude vehicles and a modern scientific balloon, which has : y now become an important research tool.

The main development has been carried out by M. Schwarzschild and his team at Princeton University in the United States, in collaboration with the United States Navy, the National Science Foundation, and the National Aeronautics and Space Administration. The 'Statoscope' flights of 1959, concerned mainly with studies of the Sun, were remarkably successful, and the project has now been extended. With Statoscope II, the over­all height from the telescope to the top of the launch balloon is 660 feet; the balloons together weigh over two tons, and another two tons of ballast are carried for later release if height has to be maintained during the night. The telescope, plus its controls, weighs three and a half tons. Two large parachutes are also carried; in case of emergency, the instruments and their records can be separated from the main balloon system, and brought down gently. Many of the radio and electronic devices used are similar to those of artificial satellites.

The launch of such an enormous, fragile system must be under­taken on a calm day, with a wind speed of less than fifteen miles an hour or so, and takes some time. The inflated launch balloon lifts the long, folded main balloon, the twin parachutes, and the telescopes with its associated instruments and controls. Two large lorries are used to cancel out any ground-wind; finally, when the long train of items is extended vertically, the tethering stay is dropped and the whole assembly rises into the upper air at a rate of 800 feet per minute.

During the ascent, helium gas from the launch balloon vents into the main balloon, so that at the chosen 'cruising' altitude (about fifteen miles) the main balloon will be fully inflated. At this point, radio commands direct the telescope towards the objects under study. The telescope locks on to each object in turn, while the observations are made. The procedure is far from simple, but is much more straightforward than with an earth satellite or space-probe; the balloon is what may be termed a 'local' vehicle, and is much more under control. The vital ad­vantage is that the actual instruments and records are recovered, to be examined at leisure and in comfort.

A model of Statoscope II left, and the balloon itself after launch right

The new telescope for Statoscope II would be regarded as very fine even by ground-observatory standards. It is a reflector, with a 36-inch mirror made of fused quartz. The entire telescope unit will be able to point to selected objects in the sky with re­markable precision, and will remain pointing steadily to an accuracy of 1 /50 of second of arc. At peak altitude, where the atmosphere is so thin, the telescope will be capable of detecting fine details on the Sun, Moon, and planets only 1/10 of a second of arc across - which is comparable to using a telescope based in London to see a man who is as far away as New York.

Important discoveries have already been made by balloon- telescope techniques. For instance, detailed photographs of the Sun's surface have been taken, showing features beyond the range of ground telescopes. It has long been known that the solar surface is 'granulated', but the individual granules are compara­tively small, and are in rapid motion, so that they are not easy to study. Balloon photographs show them with amazing clarity, and show that the granules are not of uniform size. The structure of sunspots has also been shown in more detail than ever before.

Stellar astronomy has also benefited, but in view of the present emphasis upon rocket probes it may be worth saying something about the balloon results with regard to Mars and Venus.

Mars, where there is an atmosphere - even though a thin one - has been specially studied, particularly with regard to atmos­pheric water-vapour. There is so little moisture that ground-based instruments were unable to detect it at all; its traces were masked by the water-vapour in our own air. Balloon telescopes have been able to observe from heights where terrestrial water-vapour can b e neglected, and for the first time definite traces of moisture have been found in the Martian atmosphere.

The first serious balloon studies of the second of our 'neighbour' planets, Venus, were made in November 1959, by Ross and Moore in the United States. Until then it had been tacitly assumed that the atmosphere of Venus contained no appreciable water- vapour, and the clouds, whatever they might be, were not made t: H20. The balloon results showed otherwise. Instead of being bone-dry, the atmosphere contained more water-vapour than that of the Earth at an equivalent level. These early results have been substantially confirmed by more recent balloon flights, and it also appears that the clouds are composed of ice crystals. (This does not mean that the planet's surface is likely to be refreshingly cool; Venus is almost certainly very hot indeed.)

So far as balloon astronomy as a whole is concerned, we must admit that it will always be limited in scope; a balloon, by its very nature, has a definite 'ceiling'. For studies which involve going up above the shielding layers in the ionosphere the rocket must remain our only answer. Yet there can be little doubt that balloon techniques have proved their worth, and will be widely used in the future. By space-research standards they are very cheap; the main cost lies in the telescopes and other instruments which are to be lifted - but it is not essential to use giant telescopes. Reflectors of, say, forty to fifty inches aperture probably represent the practicable maximum.

Manned ascents for scientific research have often been made, but generally speaking there is no need to risk human life. The records are obtained photographically, and a visual observer on the spot could not add a great deal, interesting though the ex­perience would be. It is the unmanned, instrument-carrying balloon, operating from altitudes of fifteen miles or so, which will prove of most value in the long run.

Almost all modern work in balloon astronomy has been carried out by the Americans, but since the results are so encouraging it is presumably only a matter of time before the Russians join in ; we may hope, too, for British participation. It is too early to say just what the next developments will be, but we may be sure that the balloon, as an astronomical tool, has come to stay.

April 30 1965 - Astronomy without a Telescope

Many viewers of The Sky at Night had written in to complain that most of the objects discussed were beyond the range of all but the telescope- owner. This, of course, is a perfectly valid criticism; the astronomer would be sadly handicapped without his telescopes. On the other hand, there is a great deal to be seen with the naked eye - when one knows where to look: and, with Henry Brinton, I did my best to point some of these out.

Subsequently, I invited viewers to make drawings of the Full Moon as seen with the naked eye, and send them in. In the next programme we showed several and I was surprised how good they were. Some of them came from schoolboys, who clearly had no access to published lunar map:, and on the whole I am surprised that pre-telescopic era charts of the Moon were not better than they actually were.

An astronomer is always pictured as a man with a large telescope. This is perfectly logical; without telescopes, our knowledge of the universe would be comparatively slight, and modern research has to be undertaken with the aid of very powerful instruments, j Yet there is a great deal of interesting observation open to the enthusiast who has no optical equipment at all, and naked-eye studies are certainly not to be despised.

The first step to be taken by the beginner is to learn the various constellation patterns, which is not nearly as difficult as might be thought. One good scheme is to select a few easily-found group: and then use these as direction-finders to more obscure constella­tions as well as bright stars. The two best 'sky marks' are Orion: and the Great Bear, both of which are prominent in the evening sky during winter, though by spring Orion has more or less disappeared in the evening twilight.

Ursa Major, the Great Bear or Plough, is circumpolar in Britain; that is to say it never sets, and is always to be seen when-1 ever the sky is sufficiently dark and clear. During May evening it is fairly high up, and makes a splendid guide. For instance, the tail of the Bear (or, alternatively, the handle of the Plough) shows the way first to the brilliant orange star Arcturus, in Bootes or the Herdsman, and then to Spica in Virgo, which is less striking "than Arcturus but which is nevertheless very prominent in the south-east. Also to be found from the Bear is Polaris, the Pole Star, which lies within a degree of the north pole of the sky, and which seems to remain almost stationary with the other celestial bodies moving round it.

Polaris is not placed exactly at the pole, as a simple experiment will show. If you take an ordinary camera, point it towards the celestial pole and then give a time exposure, the result will be a series of star-trails. The bright, short trail near the centre is that of Polaris, and the position of the true pole is easy to estimate. Pictures of this sort may be taken with no trouble at all; the only point to remember in aiming the camera is that the altitude of Polaris above the horizon is approximately equal to the observer's latitude on the Earth.

The two 'Pointers' in the Great Bear are named Dubhe and Merak; Dubhe is slightly brighter than the Pole Star, Merak a little fainter. If the line from them is extended in the opposite direction, away from Polaris, it will come to the constellation of Leo (the Lion) marked by a curved line of stars shaped rather like a question-mark twisted the wrong way round. Regulus is the brightest of these stars, which make up the so-called 'Sickle'.

It is often said that a star twinkles, but a planet does not. This is not strictly true, since a planet low on the horizon may twinkle violently, but it is correct to say that a planet twinkles less than a star, because it appears as a tiny disk instead of a mere point of light. Twinkling is due entirely to the effects of the Earth's atmosphere, so that it is most marked with objects low down in the sky.

Superficially one star looks very much like another, but the careful observer will soon notice that the colours are not all the same. Of the three brightest stars in the northern hemisphere of the sky, Arcturus is orange, Capella yellow, and Vega bluish. All three are visible during spring evenings (though Vega is ad­mittedly rather near the horizon), and it is instructive to compare them. Binoculars, of course, will bring out the different colours very well, and will also show various hues among the less brilliant stars; thus Dubhe, the senior of the two Pointers, is decidedly yellower than its companion Merak.

There are also some stars which are double, since they are made up of two components very close together. The best example of a naked-eye double is Mizar, the second star in the tail of the Great Bear, which has a much fainter star, Alcor, close beside it. There is a minor mystery about Alcor, since the old Arab astro­nomers of a thousand years ago stated that it could be seen only under good conditions and by keen-sighted observers. Nowadays this is not the case, and anyone with normal vision can see it whenever the sky is reasonably dark and there is no mist or cloud about. Telescopically Mizar itself is found to consist of two com­ponents, so close together that to the naked eye they appear as one, while one of these components is itself known to be double.

Other naked-eye pairs may be found, notably Nu Draconis in the Dragon's head and Epsilon Lyrae in the small but interesting constellation of Lyra, the Harp. Epsilon Lyra lies close to Vega, and is of special interest because it is a multiple object; each component is again double, so that we have a fine example of a quadruple star. With the naked eye, the appearance is that of two rather faint stars, very close together. Another easy pair L: Theta Tauri, in the Hyades cluster close to the brilliant reddish Aldebaran.

The naked-eye observer can also interest himself in variable stars, which brighten and fade over relatively short periods of a few days or a few months. Betelgeux in Orion is one such case sometimes it is little brighter than Aldebaran, though it has ah: been known to rival the brilliant Rigel. Other variables art Scheat in the Square of Pegasus, Mira in Cetus (the Whale), an: two of the stars in the famous W of Cassiopeia. With all these stars the variations are intrinsic, but things are different with Algol, the 'Demon Star' in Perseus, which seems to shine steadily for two and a half days at a time and then exhibits a long, slow 'wink' lasting for several hours before regaining its normal brilliancy. Strictly speaking, Algol is not variable, but is made up of two stars, one much more luminous than the other, moving round their common centre of gravity; when the fainter star passes in front of the brighter, the total light shows a decrease. With Algol, the whole cycle of changes is easy to follow with the naked eye.

Of the star-clusters, much the most celebrated is that of the Pleiades or Seven Sisters, which is prominent throughout the winter but which sets soon after the Sun by spring.

Normal-sighted persons can see seven separate stars in the group, so that the familiar nick-name is very appropriate. On the other hand, Eduard Heis, a last-century German astronomer, is reputed to have been able to see nineteen Pleiades without optical aid!

The Hyades, round Aldebaran, are brighter than the Pleiades, but are more scattered, so that the effect is not so spectacular. (Incidentally, Aldebaran itself is not a true member of the cluster; it simply happens to lie in much the same line of sight, and is only half as far away from us.) Another naked-eye cluster is Praesepe in Cancer; moonlight will drown it, but on a dark night it is by no means hard to see. It is a fine sight in a telescope, and has earned its unofficial name of’ the Beehive'.

Occasionally a bright nova, or temporary star, will appear in the sky. To be precise, a nova is not a new star; what happens is that a formerly very faint star suffers an outburst which makes it flare into short-lived prominence, though after a brief period of glory it fades back to its former obscurity. The outburst affects only the star's outer layers, so that no lasting damage is done, whereas in the much rarer supernovse the star's material is blown away into space, leaving nothing more than an expanding cloud of gas. Four supernova;, the stars of 1006, 1054, 1572, and 1604, have appeared in our Galaxy since records began; the first of these has left its debris in the form of the Crab Nebula, which is of the greatest interest to both optical and radio astronomers, but which is below naked-eye visibility. On the other hand, bright novae have been seen often enough, and some of them have been discovered by amateurs. There is always a chance that the naked-eye enthusiast will be fortunate enough to detect a nova, though it must be admitted that the chances are heavily against it.

Only three of the outer galaxies are visible without optical aid and two of these, the Nubecula; or Clouds of Magellan, are too far south to be seen in Europe. The third is the Great Spiral in Andromeda, which may be glimpsed as a dim misty speck.

So far as the Solar System is concerned, the naked-eye observer has considerable scope. He can see some of the waterless 'seas' on the face of the Moon, he can make useful observations of meteors and auroras, and he can study the artificial satellites such as the American Echo balloons.

Before the war, our knowledge of meteor paths depended almost entirely upon observations made without a telescope. The procedure was to plot the apparent track of the meteor against the stars, and estimate its magnitude and duration; if the same meteor were seen by another observer some way off the true height and path could be worked out. This sort of work is still useful, though it is only fair to add that radar methods have now been brought into play and yield more accurate results. Sporadic meteors may appear from any direction at any moment, but most of the bright shooting-stars belong to definite showers, so that some periods of the year are more favourable than others. The most consistent shower, that of the Perseids, is visible in early August; anyone who stares up at a clear, dark sky for a few minutes between, say, 28 July and 15 August will be unlucky not to see at least one meteor.

Auroras, on the other hand, are phenomena of the high atmos­phere, though their cause lies in the Sun. During 1963 and 1964 there were few bright displays, because the Sun was going through the quietest phase of its eleven-year cycle, but activity has now begun to increase again, and there should be more frequent aurora: during the next few years. Since the wonderful lights are due to particles sent out from the Sun, and these particles are magnetic, displays of aurora are best seen in high latitudes; a winter night in, say, Iceland or north Norway would be dull without them. Observers in the northern and central parts of Scotland are often able to see brilliant aurorae, though in England the opportunities are much fewer.

By now there are a great many artificial satellites circling the Earth, and a few of them are really bright, appearing as slowly- moving stars creeping across the sky. Most prominent of all are Echo I and Echo II, both American-launched and both of the balloon type; since they are larger than most of the man-made moons, and were deliberately coated with reflective material, they can hardly be over-looked, and predictions for them are given in various periodicals and daily newspapers. Amateurs have done excellent work in checking on the positions of bright artificial satellites. The procedure is to time the moment when the satellite passes between two known stars or else comes to a position which may be plotted easily on the star-chart. (Gases in which a satellite passes right in front of a star are convenient, but surprisingly rare.) The only essential equipment for this sort of work is a reliable stop-watch, together with a really good knowledge of the constellations.

Though the professional astronomer would be more or less helpless without his telescope, any casual watcher can learn much even if he has no optical aid at all. There is endless variety in the night sky, and there are many fascinating objects to be seen by anyone who knows where and when to look for them. One does not need a powerful telescope in order to take a real interest in astronomy.

April 2 1965 - Astronomy and Astrology

Over the years, I have been referred to many times as 'an astrologer'. There are still some people who confuse astrology with astronomy, and after much deliberation we decided to give a programme to the subject, prompted by the fact that at that time three planets {Mars, Uranus and Pluto) were all in the constellation of Leo.

The results were, predictably, somewhat explosive. Letters from in­furiated astrologers poured in; they ranged from organizers of 'colleges' providing 'degrees' in astrology {at a suitable fee, of course) to one earnest viewer who wrote saying that as I appeared on the television screen, my aura was dull yellow and speckled. All I could do in the latter case was to write back assuring the correspondent that I would do my best to have my aura dry-cleaned before the next programme. There were also letters from flying saucer enthusiasts and followers of the Atlantis cult. I spent many hours battling with the deluge of mail, though with regard to the 'colleges' I admit that I merely put them in touch with each other and took no further action.

The most interesting point about it all was that not one of the astrologers offered any answer to the objections I had put forward. And there were, of course, many letters too from people who were glad that I had pointed out the difference between astronomical science and 'what the stars foretell'.

At the present moment Mars is still a prominent feature of the evening sky. Though it is receding from the Earth, it is still much brighter than any of the stars near it, and its strong red colour marks it out at once. During early April binoculars or low-power telescopes show another planet close beside it; this is Uranus, the third of the remote gas-giants, much larger than either Earth or Mars, but so distant that it is never easy to see with the naked eye. A moderate telescope is enough to show its rather dim, greenish disk, though larger instruments are needed to reveal any of its five satellites.

Uranus lies far beyond Mars, and is in fact very much farther from Mars-than we are. The two planets appear close together simply because they happen to lie in more or less the same line of sight. Both are in the constellation of Leo the Lion - and yet this, too, is merely a conventional means of expression, since even the nearest star is immensely more distant than a planet.

The diagram shows what is meant. The main stars of Leo are shown, together with their distances in light-years. (A light-year, or the distance travelled by light in a period of one year, is equal to rather less than six million million miles.) The curved line of stars which includes Regulus, Gamma, and Epsilon is generally nicknamed 'the Sickle'. Mars, at the moment, is only about 75,000,000 miles away - that is to say, less than seven light-minutes!

To say that Mars is 'in' Leo is therefore decidedly misleading. .After all, a sparrow flying at rooftop-height against a background of clouds is not 'in' the clouds.

There is the further point that the stars of Leo are themselves totally unconnected with each other. Epsilon Leonis is over 250 light-years away from Regulus, which is considerably more than the eighty-four light-years separating Regulus and the Sun. The pattern of the constellation is nothing more than a line of sight effect, and if the Solar System lay in a different direction the stars of Leo might well be spread out all over the sky. In fact, a 'con­stellation' is not truly a constellation at all.

Yet these constellation groups, and the apparent positions of the planets in the sky, form the whole basis of the pseudo-science of astrology, which was widely studied in mediaeval times and which is still taken quite seriously in a few countries, notably India. It was claimed that a person's whole character and destiny was influenced by the positions of the Sun, Moon, and planets against the stars at the moment of birth, and an astrological horoscope was regarded as a most important document. Famous scientists of past times were believers in astrology; even Johannes Kepler, who laid down the famous Laws of Planetary Motion, cast horoscopes (though whether he believed in them is another matter), while the great Sir Isaac Newton was most decidedly a mystic. Still earlier, astrology was thought to be just as important as true astronomy.

Originally the Earth was thought to be flat, and to lie at the centre of the universe. The old Greek philosophers realized that the Earth is a globe, but only a few of them were bold enough to suggest that our world might move round the Sun; indeed, it was not until the sixteenth and seventeenth centuries that the idea of a Sun-centred system became firmly established. Astrology, then, is related entirely to the Earth as a centre.

The mediaeval astrologer was a most influential person. He cast horoscopes for kings and princes, he made weighty pro­nouncements, and sometimes he even predicted the approaching end of the world. Comets were regarded as particularly unlucky, but, according to the astrologers, conjunctions of several planets were even worse.

It is natural that the planets - or some of them - should at times appear close together in the sky; as we have seen, Mars and Uranus are at present only a few degrees apart. But when several bright planets met in the same constellation, in 1524, a famous German astrologer named Stoeffler took the opportunity to fore­cast the end of the world, and caused widespread panic; people even went so far as to build boats and arks so as to escape the expected flood. Much more recently, in 1962, five planets were together in the constellation of Gapricornus (the Sea-Goat), and once again the astrologers were much alarmed. In India, parti­cularly, there was great relief when the planets spread out among the constellations once more and the world still survived.

The Sun, Moon, and planets are confined to a certain region of the sky, known as the Zodiac. This is because the orbits of the planets, including the Earth, lie in much the same plane; the inclination is seven degrees for Mercury and less for the remaining planets. There is, however, one exception: Pluto, which is a relatively faint telescopic object, and was not discovered until 1930. (At present it, like Mars and Uranus, will be found in Leo.) The inclination of Pluto's orbit amounts to seventeen degrees, so that it can leave the Zodiac. This is unlikely to worry the astrolo­gers, and in any case the 'signs' of the Zodiac no longer correspond to the actual constellations, since the effects of precession - that is to say, the slight wobbling of the direction of the Earth's axis - have become quite appreciable since classical times. The vernal equinox, or point where the ecliptic cuts the celestial equator, is still known as the First Point of Aries, but by now it has moved out of Aries (the Ram) into the neighbouring constellation of Pisces (the Fishes).

Two of the other planets, Uranus and Neptune, were also unknown to the old astrologers; Uranus was discovered in 1781. Neptune in 1846. If these planets do in fact exert an influence upon human destinies, it would be interesting to learn why the astrologers did not track them down long before the astronomers could do so with their telescopes! There are also the numerous minor planets, or asteroids, which move round the Sun between the orbits of Mars and Jupiter. It is true that they are small in size, but quite a number of them are brighter in our skies than remote Pluto. One of the asteroids, Vesta, is even visible with the naked eye when best placed, whereas Neptune and Pluto, among die 'proper' planets, are always far below naked-eye visibility.

One of the biggest absurdities of astrology lies in the names of die Zodiacal constellations themselves. The familiar groups, such as Leo, Taurus (the Bull) and Gemini (the Twins) are of ancient origin, though it is worth noting that the Chinese and the Egyp­tians used a completely different system. Nobody is quite sure in which country our own constellations were first described. The old Ghaldcean star-gazers may have been responsible; astronomers in the island of Crete have also been suggested. In any case, Ptolemy, last of the great scientists of ancient times, listed forty- eight constellations in his catalogue of the stars. Ptolemy died about a.d. 180; even then, the patterns were very old indeed.

Yet few of the constellations bear the slightest resemblance in outline to the objects after which they are named. It requires considerable imagination to make a bull out of Taurus, a lion out of Leo, or a crab out of Cancer. Moreover, many of the names are mythological; Leo commemorates the Nemaean lion killed by the hero Hercules during his twelve labours. (Hercules is also in the sky, but he is not in the Zodiac, and is much less brilliant than his leonine victim.)

What was evidently done was to draw up arbitrary figures bearing little or no relation to the star-patterns concerned, and then allot names. When this had been done, the astrologers assigned 'characteristics' to the constellations according to the names that had been given. Cancer, the Crab, is said to be a watery sign. Leo, of course, is virile and positive; it is said that the Sun is at its greatest astrological strength when in Leo.

Altogether, the whole procedure seems to be an excellent case of reasoning round in a circle, and it is hard to understand how any thinking person can take it seriously. It is hardly rational to take a collection of totally unrelated stars, make some sort of a figure out of the pattern, give it a name and then claim real significance for it. One can only echo the words of the Duke of Wellington when greeted in the street by a stranger with 'Mr Smith, I believe?' 'Sir - if you believe that, you will believe any­thing.'

Some astrological predictions come true. This is only to be expected; it would be most surprising if they did not, since they cover all sorts of subjects and are usually wrapped up in suitably nebulous language. Now and again some astrologer will achieve a lucky hit, which will be well publicized. The same is true of personal horoscopes, though for every correct statement there are always several which are very wide of the mark.

One typical case may be cited. Not long ago, an astrological magazine forecast the sudden death of President Kennedy, and gave the correct month of the assassination. This prediction was regarded as a convincing justification of astrology - but it must also be related that during the previous three years the same magazine had foretold the death of President de Gaulle, the deposition of General Franco, and the removal of Dr Salazar of Portugal. It is worth noting, too, that in 1938 and 1939 British astrologers were as emphatic as they were unanimous: there would be no war against Nazi Germany.

Only the credulous will believe that line-of-sight effects 0: planets and stars will have any effect upon a man's character or life, but it is nevertheless illuminating to ask a serious astrologer just how these alleged influences occur. I did ask precisely this question of an astrologer a few months ago. His reply was: hasn’t the slightest idea.' This was, at least, a straightforward admission, and differed from the usual attitude. Most astrologer; faced with such a query, would have started talking about mysticism, ancient teachings, and, of course, vibrations. The latter word is a favourite of all devotees of what may be termed the 'fringe' of science; it is also very convenient, because in such a context it may be taken to mean practically anything.

Arguments which have no basis of common sense are always hard to refute. It is so with astrology, which lacks any scientific or logical foundation, and which is a relic of the past, when super­stition was rife and concrete knowledge was very limited. In ancient times, when the nature of the universe was not under­stood, it was natural enough to regard the Earth as of supreme importance, with the remaining bodies set in the sky merely for the sake of Earthmen; in such a climate, astrology could be ex­pected to flourish. By now it has, of course, been completely dis­credited in Europe, though in the East it lingers on.

It is, after all, virtually harmless, and many people are amused to read the 'What the stars foretell' columns in the popular press. It must also be emphasized that professional and amateur astrologers are, in general, completely honest and sincere. They take themselves most seriously; they give each other 'degrees', they put impressive-looking letters after their names, and they offer instruction to the unenlighted, all with the best of intentions. The same can be said of other equally sincere bodies, such as the International Flat Earth Society, which still exists, and the Ger­man Society for Geophysical Research, whose members be­lieve the world to be the inside of a hollow globe, with the Sun in the centre of the hollow and Australia situated somewhere above our heads.

There seems no need to say more. Astrology is not a science, and no person with any scientific background will take it seriously, but its name still leads to a certain amount of confusion. Suffice it to say that astrology and true astronomy are entirely different, and entirely unassociated. Yet the sincere astrologer does little damage, and, like the flat earther and the hollow-globe believer, he means well.