ASE-24: Observing list for beginners

ASE 1-4: THE MOON

The first time you look at the Moon through a telescope is an unforgettable moment! The clarity with which you can see the amazing range of features, in more detail than just about any other astronomical object, is staggering.

At times it can frustrate when you want to observe fainter objects and its light blots them out, but it has a beauty all of its own. The best time to observe the Moon is not normally at full Moon, when there are few shadows, but at any other phases when the Sun strikes the surface at an angle casting shadows that provide more contrast. However, there are some features that are best observed at full Moon.

To get the most out of the Moon, use software such as Virtual Moon Atlas, to help you identify interesting features. You can download it for free at https://ap-i.net/avl/en/download.

ASE-1 Lunar seas and ray craters

The Lunar Maria – or seas – are the large, dark, smooth areas formed by lava from ancient volcanic eruptions.

The major ray craters are also visible around full Moon time. Craters Tycho and Copernicus have the most complex and far-reaching systems of rays but there are other less-prominent ones such as Kepler.

Spot as many seas as you can and identify them using the chart. Identify the main ray craters and see if you can find any others.

OBSERVE: They are visible at most phases of the Moon but all are more clearly visible for a few days either side of full Moon.

Mare Tranquilitatis, the Sea of Tranquility, is where Neil Armstrong and Buzz Aldrin landed in the Apollo 11 mission in 1969.

ASE-2 Copernicus and Plato

These are two of the most interesting craters on the Moon. Copernicus is a large ray crater, 97 km wide, with several central peaks. It stands by itself just south of Mare Imbrium. The walls of the crater can appear bright white, casting long, dark shadows onto the crater floor at various lunar phases.

Plato is an impact crater, filled with lava, 109 km across at its widest point. It has a collapsed wall on the west side leading to interesting light and shadows at different illuminations.

Try and observe them at different phases and watch how the appearance changes with varying illumination. Although the floor of Plato looks smooth, there are actually several small craterlets in it. These are a real challenge to see.

OBSERVE: Copernicus is visible from about 2 days after first quarter phase (half Moon). At full Moon (lunar midday) the rays become more obvious. When the crater is on the terminator between light and dark (lunar dawn) the shadows become well-defined.

Plato is visible from 1 day after first quarter.

ASE 5-7: DOUBLE STARS

Double stars are interesting objects where two stars appear close together in the sky. The may just be a chance optical alignment in the sky or they may actually be gravitationally associated, a binary system where the two stars orbit around each other. Some double stars are so close together that it is very hard to split them, but the ones we have selected are all viewable with small telescopes and are some of the more interesting ones in the sky. Use the finder charts to locate them.

ASE-5: Albireo, Beta Cygni

Albireo is probably most people’s favourite double star because of the colour combination. It consists of a brighter yellow star with a fainter blue companion, making a very beautiful pair. Together they appear as a single naked eye star with a combined magnitude of 3, but through a telescope they are easily split into two stars of magnitude 3.1 and 5.1.

Albireo is just an optical double as the stars are separated by about 60 light years. They are about 400 light years away from us.

Find Albireo in Cygnus using the Summer Triangle as a guide. It is made up of the three bright stars Deneb in Cygnus the swan, Vega in Lyra the lyre and Altair in Aquila the eagle.

OBSERVE: The Summer Triangle is high in the sky during Summer months and early Autumn.

ASE-6: Epsilon Lyrae

Epsilon Lyrae is interesting because it is actually a double-double. The two brighter stars that make up Epsilon Lyrae, Epsilon 1 and 2, are themselves double stars.

The two brighter stars are easy to separate but the companions of each are much closer together and will be tricky to split unless you have really good seeing and sharp optics.

• Epsilon 1 stars have magnitudes of 4.7 and 6.2 separated by 2.6″
• Epsilon 2 stars have magnitudes of 5.1 and 5.5 separated by 2.3″

The brighter two stars are an optical alignment, but both stars are actually binary systems themselves.

Locate using the Summer Triangle as a guide.

OBSERVE: The Summer Triangle is high in the sky during Summer months and early Autumn.

ASE 8-12: PLANETS

Of course the planets are an obvious target for amateurs and can be very rewarding – but also disappointing at times. One of the biggest challenges when observing the planets is the seeing. Seeing is all about the stability of the atmosphere. When the seeing is bad the image in your telescope seems to boil and you can’t make out any fine details. On the rare occasions when seeing is good you can get exquisite views. The amount of detail you see on planets is dependent on telescope aperture and seeing.

ASE-8 Jupiter moons and cloud belts

Jupiter is a fascinating body to study because of its ever changing cloud belts and the dance of its 4 main satellites – the Galilean moons – Io, Europa, Ganymede and Callisto, so called because they were discovered by Galileo Galilei in 1610 (using a very small telescope). You should easily be able to make out the two main north and south equatorial belts. On nights of good seeing you may even be able to glimpse the Great Red Spot and shadows of the moons as they pass in front of the planet, but this may be harder in a small telescope. Try and identify the 4 main moons on different days, using a guide such as https://in-the-sky.org/jupiter.php. To see any details on Jupiter you may need a higher magnification but this won’t achieve much if the seeing is bad.

OBSERVE: Follow our Sky Diary for when to observe the planets.

ASE-9 Saturn Rings

No-one ever forgets their first view of Saturn through a telescope! It is a very surreal sight, seeing the pale yellow planet surrounded by its ring system just floating there in space. Definitely one to share with friends and family.

Not much detail is visible on the surface of Saturn using a small telescope but you can make out the main division in the ring system – the Cassini Division – on nights of good seeing.

ASE-10 Venus phases

With the naked eye Venus is a dazzling morning or evening star. Through a telescope it goes through various phases in a similar way to our Moon. Try and keep a track of the phases through an evening or morning apparition. Larger telescopes can show faint, dusky markings on the clouds of Venus but you are unlikely to see much apart from the phases with a small telescope.

For safety reasons you should only observe Venus once the Sun is below the horizon. 

ASE 13-16: NEBULAE & GALAXIES

We’ve all seen the fabulous images of galaxies and nebulae taken by some of the biggest telescopes in the world and by the best astrophotographers. Obviously it’s not going to be possible to see them like that through a small telescope but there’s something amazing when you see an object thousands or millions of light years away with your eye and your own small telescope. The light from those objects started out the journey towards your eye many years in the past and you’re seeing these objects as they looked then. Take your time and the longer you look the more details you will see.

Planetary nebulae have nothing to do with planets although they are often circular. The term comes from the fact that early astronomers though they looked a little like planets. In reality they are caused by stars that have thrown off large amounts of material, glowing because the gas is excited by a nearby star.

Nebulae are interstellar clouds of gas and dust. Some glow because they are excited by the radiation from nearby stars; others glow because they reflect the light of the stars around them.

ASE-13 M42 Orion Nebula

It is very hard to miss the constellation of Orion when it rises in the Winter skies. The equally famous Orion Nebula is also easy to find just below three stars in Orion’s belt. View it on dark, moonless nights and you will see more of the fainter nebulosity. Take your time and let your eyes adapt to the darkness and you will keep seeing more detail. Try and make out the four central stars – the Trapezium. These are the stars that excite the gas cloud and cause it to glow.

OBSERVE: Orion is definitely a Winter object, visible in the south from November to February.

ASE-14 M31 Andromeda Galaxy

The Andromeda Galaxy is probably the most well known galaxy and the closest large galaxy to our own Milky Way. It is also the furthest you can see with the naked eye at 2.5 million light years!

Andromeda itself is not an obvious constellation but you can find it by locating the square of Pegasus then following the top left corner of the square to the left for two stars then go “up” to find the galaxy.

M31 is a very large object in the sky – about six time the size of the full Moon, so it should fill your field of view. The glow of the central bulge is obvious and you may also be able to make out some of the dark dust lanes and fainter spiral structure under dark skies. M31 has two satellite galaxies, M32 and M110, but these are much harder to see.

OBSERVE: Andromeda is best seen in late Summer and Autumn.

ASE 17-19: GLOBULAR CLUSTERS

Globular Clusters are spherical groups of stars that surround our galaxy in a halo. They are very distinctive in shape, almost looking like an explosion of stars. In a telescope they are seen as fuzzy patches with some of the individual stars being resolved with larger telescopes. All are very similar in appearance but different in size and setting against the background stars. These are the three brighter ones seen from the northern hemisphere. There are about 150 known to be surrounding our own galaxy.

ASE 20-24: OPEN CLUSTERS

Open Clusters are also known as Galactic Clusters (not to be confused with Galaxy Clusters which are clusters of galaxies) because they exist within our own Milky Way galaxy. They are groups of stars loosely associated with each other and bound by gravitational attraction. They take many different shapes, sizes, brightness, colours and numbers of stars. Some are embedded in gas clouds which can be excited by the stars or simply reflect the light of the stars.

ASE-20 M45 Pleiades – Taurus

The Pleiades star cluster is probably the most well-known and easiest to see with the naked eye. It is quite a large cluster at over three times larger than the full Moon in the sky. It is surrounded by its distinctive blue nebulosity which reflects the light of the hot young blue stars that make up the cluster. Most people can make out 6 or 7 stars with the naked eye, but there are many more visible through any small telescope.

You can find M45 by following the line of Orion’s belt upwards until you reach the bright reddish star Aldebaran in Taurus and the follow the line a little further until you reach the Pleiades. Hard to miss.

OBSERVE: Taurus is a Winter constellation and is high up in the South from November to January.

ASE-21 M35 Gemini

M35 is a beautiful cluster on the edge of Gemini, at just about naked eye visibility. It is relatively easy to find once you have found the twins of Gemini, Castor and Pollux. It is about the size of the full Moon in the sky.

There is actually a smaller, fainter cluster on the south-west edge of the cluster, NGC 2158. It is much fainter but you may just be able to spot it. It is not associated with M35 as it is about 9,000 light years further away.

OBSERVE: Gemini is a Winter constellation and is best viewed in December and January.

ASE-22 M34 Perseus

M34 is another easy to find cluster, on the edge of naked eye visibility. There are a handful of brighter stars and many fainter ones. It lies between Perseus and the ‘W’ of Cassiopeia, just to the right of Beta Persei, the bright star Algol.

OBSERVE: Perseus is usually high in the sky in northern latitudes so is visible all year round. It is best seen in the evenings in Autumn and Winter months.