Starguide: August

By Jenny Winder

What to look out for in the August night sky

We will be treated to not one but two full Moons this month. The first occurs on August 2nd and the second, or Blue Moon will be on August 31st. A Blue Moon used to mean any season that had four instead of the usual three full Moons, but is now generally accepted as being the second full Moon in any month. Although the term has come to be associated with a very rare event, on average we get a blue Moon every 2.66 years. You’ll have to wait until July 2015 for the next Blue Moon. We have no such special name for the second new Moon in a month although this happens as often, in fact if two new moons occur in a month, it usually follows that, four years later, two full moons will also occur in the same month.

Luckily the Moon will have faded to a pale waning crescent by August the 12th when the Perseid meteor shower peaks. This is one of the best showers of the year, producing fast, bright meteors that often leave persistent trails. The shower radiates from the constellation of Perseus to the Northeast and can have a Zenithal Hourly Rate (ZHR) of between 50 and 80 meteors. These represent the debris left behind by the comet Swift Tuttle.

The planets are all on display this month. Saturn dips to the western horizon in the early evening just after sunset, to be joined later in the month by Mars near Virgo’s bright star Spica . The three will form a line on August 14th and an equilateral triangle on the 21st. Around midnight, by the end of the month, Uranus will be in Pisces to the south while Neptune lies in Aquarius, reaching opposition on August 24th. In the morning, just before sunrise, Mercury lies in Cancer on the eastern horizon, with Venus above in Gemini and Jupiter higher again in Taurus.

The Summer Triangle still presides over the skies and it’s three main constellations contain many objects worth noting. Albireo in Cygnus lies toward the centre of the triangle. Even a small telescope will show that it is actually a superb double star, the brighter yellow star is itself a close binary system that contrasts beautifully with the fainter blue companion star. Cygnus also hosts The Veil Nebula Complex covering an area roughly 3 degrees in diameter andthe North America Nebula NGC 7000 which lies just to the left of Deneb. Two smaller constellations in the Summer Triangle areSagitta the arrow, which contains the star cluster Collinder 399 known as Al Sufi’s Cluster or Brocchi’s Cluster. The brighter members of which form the Coathanger asterism. Just above Sagitta lies Vulpecula, the little fox, whose alpha star Anser, represents a goose held in the fox’s jaws, binoculars show this is an optical binary system .

One event not to be missed this month is the landing on Mars of NASA’s Mars Science Laboratory rover Curiosity. This is the biggest planetary lander ever built and carries the most advanced payload of scientific gear to be used on Mars. Weighing 900kg and the size of an SUV it will employ the most complex landing procedure ever attempted, called the Seven Minutes of Terror. On August 6th At 05:31 am UTC Curiosity will enter Mars atmosphere at 21,000 km/h and within 4 minutes, will slow to 1,700 km/h. 10 km above the surface a 16 m parachute will deploy, slowing the lander to 360 km/h at 2 km above the surface. The entry capsule’s back and heat shields will jettison, exposing the rover attached to a Sky Crane with 8 retro rockets. The lander brakes for less than a minute, stopping the Sky Crane 20m above Mars’ surface, when 3 cables will lower Curiosity till its 6 wheels touchdown and the cables are released. You can find information, videos and links to watch full coverage of the landing here

Starguide: July

By Jenny Winder
 What to look out for in the July night sky

This month the sky is presided over by the magnificent Summer Triangle that comprises the stars Deneb in Cygnus, Lyra in Vega and Altair in Aquila.

The Moon will be full this month on July 3rd and new on July 19th. On July 15th the Moon will occult the planet Jupiter between 01:00 UT and 02:30UT. How close the occultation appears depends on your location. For the Southeastern corner of UK the occultation will be full with Jupiter disappearing from sight behind the waning crescent moon. Most of Southern UK will see the Moon grazing Jupiter, while the rest of us will see a near miss, but the pairing will still be worth looking at or trying to capture.

Three minor planets join the big boys in the skies this month. Ceres is the largest asteroid in the inner Solar System. Now designated a dwarf plant it represents a third of the mass of the asteroid belt and ; Vesta, the minor planet is the second most massive asteroid and is currently being orbited by NASA’s Dawn spacecraft. From midmonth these two will join Jupiter and Venus in the predawn sky and will travel through the Hyades in Taurus towards the Northeast. At the beginning of July Mars and Saturn can still be seen low in the constellation of Virgo in the Southwest as the Sun sets. Mercury will reach greatest eastern elongation on July 1st. This is when the planet will be furthest from the Sun, as seen from Earth, and the best time to view the innermost planet. Look for Neptune and Uranus an or so past midnight, toward the end of the month. Neptune to the South in Aquarius while Uranus is to the Southeast in Pisces. ; Throughout July Uranus is joined in the sky by Pallas, the third of our minor planets this month and possibly the largest irregular shaped object in the Solar System.

The Summer Triangle contains quite a few deep sky objects. The magnificent Ring Nebula M57 is in Lyra just below Vega. This is a beautiful planetary nebula, a shell of ionized gas from a dying red giant star. M27 is the Dumbbell Nebula in Vulpecula or little fox constellation. This is another gorgeous planetary nebula with the largest known white dwarf star at its heart. The Summer Triangle points the way down to Sagittarius, the archer. This lies between us and the very centre of the Milky Way making it one of the richest areas of the night sky. The emission nebulas, M8 the Lagoon nebula and M17 called the Omega, Swan, Lobster or Horseshoe nebula are found here along with the Trifid nebula M20 which contains an open cluster, an emission, reflection and a dark nebula.

We are now in the peak of noctilucent cloud season. For a chance to see these thin veils of blue shining clouds, look low in the Northeast before midnight or low in the Northwest after midnight. July 29th is the official peak of the Delta Aquarid meteor shower, although they can be seen from late July through to early August. They are produced by the Marsden and Kracht Sungrazing comets and have a radiant low in the Southeast and a zenithal hourly rate (ZHR) of between 15 and 20.

Starguide: June

By Jenny Winder

What to look out for in the June night sky

All eyes will be on the transit of Venus at the start of the month, but  there is plenty more for stargazers to look forward to in June.

The Moon will be full on June 4th and there will be a partial lunar eclipse visible across most of Australia, the Pacific Ocean, North and South America. It begins at 08:48 UTC and ends at 13:18 UTC. Greatest eclipse will be at 11:03 UTC when 37% of the Moon around crater Tycho will be dark and take on a red colour due to refraction of sunlight through Earth’s atmosphere.  New Moon will be on June 19th and Summer Solstice occurs for the Northern hemisphere at 23:09 UTC on June 20th. From then on the nights will get longer.

The big show happens between June 5th and 6th when Venus makes the last transit across the face of the Sun this century. Transits happen in pairs, after 121.5 years  a pair of transits occur 8 years apart, then 105.5 years pass before another pair of transits with an 8 year gap between and the pattern repeats. So the next transit after this wont be until 2117. There have only been 6 transits since the invention of the telescope and only 4 since the invention of photography. Transits have been used in the past to calculate the distance to the Sun and the size of our Solar System. This transit will be visible across most of the globe, apart from much of West Africa, the Atlantic & South America. The UK will only see the tail end of the transit after Sunrise at around 04:47 BST. Times for the transit are: First contact at 22:03 UTC  June 5th. Greatest transit at 01:29 UTC  June 6th and last contact at 04:54 UTC June 6th. You will need to find a good location with a clear view of the Eastern horizon. Remember you must never look directly at the Sun, be sure to use proper solar filters or eclipse glasses to view this once in a lifetime event.

Three related constellations grace the night sky to the South this month. Lying beneath the keystone of Hercules, Ophiuchus, (the Serpent Bearer) bisects the Serpens constellation in two holding the serpent by its head (Serpens Caput) and its tail (Serpens Cauda) With prolonged astronomical twilight at this time year we are firmly in globular cluster season and Ophiuchus boasts no fewer than 33 of them. M10 and M12 were both discovered in 1764 by Charles Messier. M10 is about 83 light years across and 14,3000 light years away while M12 is 73 light years in diameter and 15,700 light years from Earth. M5 in Serpens Caput is 655 light years across, making it one of the largest globular clusters known. It is also one of the oldest associated with our galaxy at 13 billion years old. M16 in Serpens Cauda is the amazing Eagle Nebula an active star forming region that contains the open star cluster NGC 6611 and also the ‘Pillars of Creation’ made famous by the 1995 image taken by the Hubble Telescope.

What’s in a name?

By Adam Stevens

We’ve been discovering a lot of exoplanets recently. They have such exciting names as HD 189733 b, or Gilese 581, or sometimes vaguely amusing ones like OGLE-2006-BLG-109Lb (ha ha). The most exciting ones, like those that inhabit the habitable zone of their star, and that could be like our own little Earth, get extra special names. Like Kepler-22b.

There are people that want to change this. A paper in 2009 petitioned for exoplanets to be named with a little more imagination, along the lines already established for naming planets and stars. So many of the astronomical objects that we know of are named for the myths and legends of ancient Earth; why shouldn’t this continue? The IAU, the regulatory body for the naming of things we find in space, oppose the idea of ‘naming’ the new planets that we discover, mainly because the are likely to be so many that we would soon run short of names. Yet these exoplanets are given names, just rubbish ones that tell non-astronomers absolutely nothing about them.

Does the name we give them really matter, other than offering a way of relating these strange astronomical objects to things that we mere mortals know, offering us a way of picturing these planets in our mind’s eye?

The practice of naming objects in the sky for characters from myth and legend dates back, at least in the West, all the way to the Greeks and Romans. What primary school classroom would be complete without an atlas of the planets, secretly listing a portion of the pantheon of old Roman gods?

Mercury, messenger god with winged sandals, and the planet that moves fastest across the sky. Venus, the bright and beautiful morning star, also the goddess of love and beauty. Mars, god of war, the spot of blood red that wanders the night. Jupiter, king of the gods and king of the planets, protector of the solar system. Saturn, the furthest planet visible to the ancients, which the Greeks made sacred to Cronos, father of Zeus, the Romans eventually doing the same. These names have survived for more than two thousand years.

In those days, before the invention of the telescope, these were the only wanderers visible in the night sky. Later, when astronomers found more ‘planetes’, the Roman system of naming was already in place, so that despite the protestations of their discoverers (Herschel wanted to name Uranus after King George III) we ended up with the outer planets Uranus, Neptune, and, eventually, Pluto.

The power of this naming convention went even further. When the two moons of Mars were discovered, they quickly became Phobos and Deimos, the war god’s attendant sons. The moons of Jupiter are all named for his (numerous (and not necessarily female)) lovers. Saturn’s moons are named for his brother Titans; Iapetus, Tethys, Dione, and, er, Titan…

At this point, though, the astronomers must have been starting to run dry of appropriate Greek and Roman myths, or at least getting bored of them. The moons of Uranus, then, are named after spirits from literature (mostly Shakespearean), like Oberon, Ariel, Miranda, and Ophelia.

Even then, we are left with many unnamed objects left in the solar system. The smaller moons, the asteroids, the comets; the most notable of these all carry names, some following the same Roman system.

More importantly, these already titled bodies are not just featureless balls floating through space. They have complex surfaces, landscapes covered in strange and wonderful features. So next up, astronomers had to devise a system for naming planetary features, and this is where they really went to town.

Some of the systems have some kind of logic.

The surface features of Venus are all, appropriately, named after famous women, sometimes real, sometimes fictional. What this says about poor old James Clark Maxwell, who has a venereal (yes, you read that right) mountain range named after him, is anyone’s guess.

The craters on the asteroid Eros are named for famous lovers.

The tortured and chaotic surface of Io is covered in the names of fire and sun gods from a multitude of ancient cultures.

Others are somewhat random, maybe because their namers ran out of good ideas, or because they were being playful: the fractured ice crust of Europa bears a heavily Celtic influence, whereas Ganymede is a melting pot of Phoenician, Babylonian and Egyptian names, both for no apparent reason.

Some give us a glimpse of some strange senses of humour. The bleak surface of Mercury is covered  from horizon to horizon in craters named after famous artists. Titan, with its thick atmosphere, lakes, and rains of liquid methane has a number of features named for rain gods and, for no apparent reason, others after gods of happiness. Perhaps it’s the weather.

These planets and moons show all the eccentricities of town planners that name the streets of a new town after their own personal interests, likes, or random topics vaguely associated with the location.

Yet none of them match the idiosyncrasy of Mars.

Details of the red planet are easily observable with even a moderately powered telescope, and so names have been assigned to these features for hundreds of years. In fact, the system we use today owes a heavy debt to the observations and imagination of Giovanni Schiaparelli, the man who gave us the “canali.”

If you look at Mars, it is easy to pick out areas of light and dark, known as ‘albedo’ features. Seeing these vast continents, pools or fractured channels of dark red on the martian landscape, Schiaparelli went about naming. Who knows what guided his thoughts, but the names of his albedo features  were drawn from influences far and wide.

Some came from classical antiquity, Olympus Mons being a prime example; the home of the gods and largest mountain in the solar system. Yet many seem totally random. Olympus Mons’ neighbours, the other Tharsis volcanoes are named, respectively, after Schiaparelli’s original Peacock lake, Rural lake, and an old Roman forest.

No matter how random, though, these names and the ones that followed them have a lyrical quality. Tempe Terra, the land of time; Promethei Sinus, bay of Prometheus; Ophir Chasma, valley of gold, and so on.

Later, with more powerful telescopes, and close up photographs of the planet, we began to see more of the details of Mars, and many of Schiaparelli’s conventions were followed. Now Mars is covered in valleys, plains, mountains named after many features on Earth. The major craters are named after famous scientists.

So if you were to look into the meanings of all these names, this “system” would probably seem mad or, at the very least, utterly arbitrary.

These names form the language of Mars and, with their fellows on other bodies, they form the language of our solar system. They evoke a past age, of a time when the gods walked amongst men, when the stories of heroes were told around fires and passed down from generation to generation. Others recall the age of exploration, when scientists were changing the world almost every day, spreading the knowledge of humanity throughout the universe.

To science, the names don’t matter. They are only designations, for ease of reference, to differentiate similar things.

For the rest of us though, these names do matter. They tell a story, a great story, of how far our species has come, but continue to remind us of where we came from.

It is sad then, when these names come into dispute. The Mars Science Laboratory, Curiosity, is due to land in Gale Crater on Mars soon. Its mission is to explore the central uplift peak of the crater, a moderately large mountain that might tell us much about the process that shaped the surface of the planet.

Before it gained notoriety, this summit hadn’t been given an official name, so the scientists working on the mission had named it after Robert P. Sharp, one of the founders of the field of planetary science, a fitting memorial for a man who spent much of his life researching Mars. Recently, though, the IAU, those responsible for those horrible Exoplanet designations, have renamed Mount Sharp to follow the standard convention, and now Curiosity will be exploring Aeolis Mons.

Yes, the system was in place, and is helpful in that it provides consistency. But peek under the lip of this consistency and you find a mass of contradiction and whimsy, so does it really matter that much?

Well, it matters to those that worked with Sharp, those who named a mountain after him. It matters to those of us that want to excite people about the discovery of planets outside our solar system. The names do matter, but they matter more in our hearts than in our head. These names are a tool to tie the real exploration of the universe to our great gift - imagination.

(Postscript: The IAU have named a crater, near Gale, “Robert Sharp” (as there was already a Sharp Crater), following their system and still preserving this legacy somewhat.)

Starguide: May

By Jenny Winder

What to look out for in the May night sky

Starwatchers have plenty to occupy themselves with this month.  The  Full Moon on May 6th  will coincide with the peak of the Eta Aquarid meteor shower in the East, cutting down the zenithal hourly rate (ZHR) considerably from its usual 40 meteors per hour. New Moon will be on May 2oth and on May 26th the waxing crescent Moon will occult M67, an open cluster of stars in the constellation of Cancer.

Venus is nearing the Sun in preparation for the transit across its surface in early June, so the planet dips below the horizon shortly after sunset. If you are quick you will see Venus’ crescent phase grow in diameter as the month progresses, from 37 arcseconds at the start of May to 56 arcseconds at the close of the month. Now is also a good time to look for the elusive Ashen Light, a subtle glow on the unlit part of Venus, similar to earthshine seen on the Moon, but much fainter. This phenomenon was first described in 1643 but has never been verified. Many have claimed to see it, but many more have not. Nobody has been able to image it and nobody knows what causes it. Saturn is still a spectacular sight low toward the South in Virgo, with the rings well displayed and  casting shadows on the surface of the planet, while the shadow cast by the planet onto the rings will grow more prominent with time.

Virgo still fills the Southern sky so take the opportunity to look at the Virgo Cluster of galaxies. There are as many as  2000 galaxies in this cluster which comprises the heart of the Virgo Supercluster, part of the Local Group of galaxies that includes our own Milky Way. The Cluster is made up of a mix of spirals and elliptical galaxies

The globular cluster M13 in Hercules lies high in the South, between the Summer sky’s two brightest stars: Arcturus in Boötes to the right & Vega in Lyra to the left. Hercules is easily recognised by its ‘Keystone’ asterism and M13 lies along side nearest to Arcturus.

To the right of Arcturus lies the small constellation of Coma Berenices, containing eight Messier objects including M53, another globular cluster of stars and the Black Eye Galaxy M64 with its distinctive dark band of dust that gives this spiral galaxy its name.

We are now entering the season of nocilucent clouds. Most of the time astronomers curse the sight of clouds for obscuring the stars but these clouds are eagerly awaited. At this time of year, between May and August the Sun remains close to the horizon and illuminates the layer of water ice that lies between 76 km and 85 km in the part of Earth’s atmosphere called the Mesosphere. The clouds appear as a fine veil of glowing blue filaments. Look low in the Northwest from 21:00 and 23:00 UT or between 01:00 and 03:00 UT low in the Northeastern sky.

By Jenny Winder

Astronomy-Amateur Author: Halfblue via Wikimedia-Commons

What to look out for in the April night sky

The constellation Leo dominates the Southern sky this month. Look for the ‘Sickle’ asterism  like a back to front question mark with the bright star Regulus at the base. On April 3rd look for Mars near Regulus above the almost full Moon. On April 15th Mars reaches its stationary point, halting in its westward journey across the sky, before moving back eastward from April 16th.

Venus and Jupiter are going their separate ways after giving us a spectacular conjunction last month and we will lose Jupiter from the night skies by the end of the month. Venus is still brilliant enough at magnitude -4.4 to be seen in daylight, setting in the northwest after midnight. On April 2nd to 4th it will pass through the Pleiades in Taurus. By April13th it will form a triangle with the Pleiades & Hyades & they will be joined by the waxing crescent Moon on April 23rd.

Saturn, near Spica in Virgo to the left of Leo, reaches opposition to the Sun, as seen from Earth, on April 15th. This means it will be visible all night. It is also closest to Earth in its orbit so bigger & brighter. The rings are currently at a favourable tilt to Earth and appear brighter during opposition due to the Seeliger effect: usually the particles that make up Saturn’s rings cast shadows on the particles behind, making them darker, but during opposition the shadowed particles are hidden behind the fully illuminated particles with the net effect that the rings appear at their brightest.

Also in Virgo,  below the main pattern of stars, lies the Sombrero Galaxy, M104. This unbarred spiral galaxy is a magnitude 9.5 and  28 million Light Years from Earth. It contains one of the most massive, supermassive black holes ever measured in a nearby galaxy.

The Moon this month will be Full on April 6th and New on April 21st. Luckily this New Moon coincides with the peak of the Lyrid meteor shower, giving the best conditions (clear skies permitting) to view the typically bright trails of this shower. The Lyrids were first noted by the Chinese in 687BC which makes them the oldest meteor shower recorded. They are caused by the debris from Thatcher’s comet and usually have a Zenithal Hourly Rate (ZHR) of 10 to 20, this is the typical number of meteors seen per hour, under the ideal conditions of a dark sky, if the radiant were directly overhead. The lyrids have been known to produce unexpected peaks of up to 100 meteors per hour so is worth making the effort to see. The radiant lies in the constellation of Lyra which rises at about 10pm in the Northeast. Wrap up warm & either lie on the ground or in a reclining garden chair. Look about 45 degrees from the radiant or most meteors will pass either side of  your head.  As with all meteor showers the best time to view them is after midnight, the hours before dawn being best as the Earth’s rotation brings the observer to a position where the meteors are striking our atmosphere head on.