January - Gemini and Orion

The key to astronomy is knowing how to get around. When travelling to another country we familiarize ourselves with its cities using maps and the same can be said for the sky – we need to familiarize ourselves with it before we can explore it properly. Whether you want to become an amateur astronomer or simply enjoy the vista as you lie back on your deckchair and impress your friends with your deep knowledge of the heavens, understanding the constellations will literally open new horizons.

Being able to recognize patterns in the night sky is indispensable – not only is it an enjoyable exercise in itself, it also helps you make heads and tails of the countless dots and points of light, and use them to find other, fainter, deep sky objects. As you become acquainted with the stars, these randomly scattered points of light will take shape into familiar patterns recognizable at a glance.

As promised in the first entry of this guide, throughout the year we’ll explore 12 constellations of the zodiac as well as a few other constellations, discovering the wealth of objects found within their boundaries. Our journey begins with one of these few others: Orion, probably the most familiar pattern in the sky, and perhaps also the loveliest for Maltese and Northern Hemisphere observers.

According to Greek mythology, Orion was a powerful hunter, whose death was either brought by the bite of a Scorpion, or by a fatal blow from Artemis. In the heavens, Orion is standing next to the river Eridanus with his two hunting dogs Canis Major and Canis Minor, fighting Taurus the bull. Another prey of his, Lepus, the hare, can be found just beneath Rigel; it is a faint constellation made of relatively faint stars, but the zigzag pattern can be made out with only a slight effort.

Orion is easily distinguishable in the night sky and stands out with its unique pattern and the wonderful and incredibly symmetrical asterism of Orion’s belt: three equidistant stars forming a diagonal right in the middle of the constellation. A good place to observe Orion this month is Dingli Cliffs – Orion rises on the dark sea below to the south. Look for it somewhere above Filfla; you should easily spot the unmistakable pattern of stars making up Orion.

Now is the time to put your binoculars to use. The Orion Nebula, situated just below the three stars and seen as a fuzzy white patch with the naked eye, provides an amazing view with binoculars. One should be able to discern the nebulosity and make out the bright specks of light, which are newly-forming stars.

Orion is extremely helpful in finding other constellations. We can find two zodiacal constellations by drawing an imaginary line through the constellation’s major stars: Gemini can be traced by drawing a line joining the two brightest stars of Orion: from Rigel at the bottom right corner of the constellation, all the way through to Betelgeuse, found at the top left corner, and continuing along this line till we come by the two bright stars of the twin brothers Castor and Pollux, while Taurus can be found by following the three stars marking Orion’s belt and moving along an imaginary line to the right till we reach a bright scarlet star, Aldebaran, marking the bull’s eye.

There are in fact many other interesting objects in the January sky. And yet Orion is so spectacular, so laden with interesting objects that it is enough to captivate anyone’s interest.

Betelgeuse is a bright star, yellowish in appearance, and marks the Hunter’s right shoulder. It is a huge star, its diameter being larger than Mars’ orbit. Rigel marks Orion’s left knee and is the brightest star in the constellation.

The region of Orion’s Belt makes for wonderful sky sweeping with binoculars, as these reveal a multitude of stars. A number of the constellation’s stars can be seen as double using binoculars, and two of them can be found here. Both Mintaka and Alnitak, the two outer stars of Orion’s Belt, are in fact double stars.

Finding these and other noteworthy objects in Orion is particularly rewarding, but a leisurely sweeping of this magnificent constellation is also very satisfying.

Orion is visible in the night sky from October to March.

We’ll now make use of the technique of star-hopping, which basically is finding your way around the sky by hopping from one constellation to another, by using them as reference. As already noted, Orion is ideal for this as it points the way to a number of constellations.

As we have already seen, we can find Gemini by finding Rigel and drawing an imaginary diagonal line crossing the whole of Orion to Betelgeuse. Now continue with that line until you reach two stars: these are Castor and Pollux, the twins. We have just star hopped from one constellation to another, namely from Orion to Gemini. (For more information on how to star hop, including an informative visual tutorial, visit: http://www.astrocentral.co.uk/starting.html)

In Greek mythology Castor and Pollux were the twin sons of the Spartan Queen Leda and the king of gods, Zeus (though according to other versions of the myth Castor’s father was Tyndareus, king of Sparta), and brothers of Helen of Troy. Castor was killed by his cousin Idas as a result of an argument over some meat (they certainly took things seriously back then), who in turn fell victim to a thunderbolt hurled by a furious Zeus, whereas Lynceus, Idas’s brother was killed by Pollux. Zeus placed the twin brothers among the stars and they became the constellation Gemini, with the two brightest stars bearing their names: Pollux is the slightly brighter star, above it lies Castor.

Gemini is not a very interesting constellation for naked-eye observers, though it holds wonders for those equipped with a telescope. Castor, for instance, is in reality a multiple star system comprising of 6 stars, three of which can be resolved in small telescopes.

M35 is a cluster that can be found at the opposite end of the constellation, slightly above Eta Geminorum, and is a spectacular view in binoculars. M35 is a magical cluster, as stars seem to miraculously appear from nowhere the longer you look at it.

The Eskimo Nebula is another celestial jewel that this constellation offers to those availing of telescopic sight. It is unfortunately too faint to be seen in binoculars.

Try to familiarize yourself with these two constellations and Orion in particular, since it will prove to be a useful signpost for finding other constellations. The sky should already be taking some form with knowledge of these new distinguishable patterns of stars, and you should already feel better orientated when looking at the heavens. Next time we’ll take a look at another two interesting constellations.

The International Year of Astronomy - Our Journey Starts Here

In honour of astronomy – this year being the International Year of Astronomy – I have decided to embark on an astronomic journey of astronomical proportions, of discovery and perhaps self-discovery, and overflowing with other ill-devised puns.

I shall be exploring the night sky each month of the year, documenting the observations in easy to read articles, with the hope of providing an easy-to-follow guide to the Maltese night sky, and perhaps induce a love for what is surely one of the most enjoyable and accessible hobbies in the world.

The monthly articles are aimed at Maltese people first and foremost, in order for them to be able to enjoy the visual splendour of the heavens and discover the mysteries of space, but can be of use to most people in the Northern Hemisphere.

Astronomy is one of the oldest practised hobbies in the world. The reason for this is fairly obvious: at its most basic form, astronomy can be practised with the most rudimentary tools available to us all, and its wonders can be enjoyed with the naked eye – all one needs to gaze at the stars is a clear sky and a dark location. Astronomy can be practised by anyone, anywhere on Earth. What better way to unite the people of the world than under the umbrella of the night sky?

2009 is the International Year of Astronomy – a year which marks the 400th anniversary since Galileo explored the heavens with one of the first astronomical telescopes. It is also the 40th anniversary of the Apollo mission that landed Man on the Moon. The IYA will be celebrated through various activities throughout the world, making it a truly global celebration of astronomy.

Anyone can partake in this world-wide celebration, and I hope that this guide will be of help to anyone who wishes to join in this other-worldly adventure.

Each month we shall explore one constellation of the zodiac, as well as some other constellations and other interesting celestial objects. For astronomers the importance of the zodiac is minimal, but the zodiacal constellations do provide an easy reference point for marking the paths of the Moon and the planets. For instance, knowing that Jupiter is near Sagittarius can be helpful in spotting it and, especially for Maltese observers, in choosing an appropriate site to view it from.

No special equipment is necessary – your eyes and a modest pair of binoculars (7 x 30 or 10 x 50 ideally) will do. Telescopes reveal more detail, but binoculars are enough for the beginner, opening a world of wonders invisible to the unaided eye.

Note: The monthly guides are meant for everyone to enjoy and are therefore kept as simple as possible, highlighting only the brighter celestial objects. However there are many other things to explore if you’re hungry for more and up to the challenge. (See the links section below for some useful resources).

Sky Watching Tips:

• During winter in particular temperatures can drop considerably at night while observing in the open air, so make sure you wear warm clothing. Wearing layers can be advantageous since you can remove or add clothing as desired. I cannot emphasise enough the importance of wearing a beanie or some other head garment in winter – covering your head is essential in order to keep warm since this is where most of our body heat escapes from.
  
  
• It’s best to observe stars, clusters and other deep-sky objects on moonless nights (new moon) or when the moon is in its last quarter since it rises late at night, giving you a chance to explore the fainter objects of the heavens, which would otherwise be dimmed by the powerful light of the moon.
  
  
• Try to stay away as much as possible from any light sources – city lights, street lights, headlights – as these will prevent you from seeing the fainter objects in the sky.
  

Links:

Here are some links that you might find useful in your exploration of space:

http://stardate.org/ – contains various information and resources that beginners should find very useful, including a moon phase calendar.
http://www.skymaps.com/ – a very informative site where you can download monthly star charts with a map of the night sky and a list of the brighter and more interesting celestial objects that are visible in that particular month. Ideal for those who would like to venture deeper into space and unravel the mysteries of the night sky.
http://www.skyviewcafe.com/ – An online planetarium showing how the various constellations and other celestial objects will appear from your location at a given time. Indispensable for accurate pre-planning of an observation session.

Glossary:

Asteroid: An asteroid is a rocky celestial body orbiting the Sun. They are bigger than meteoroids and similar to, but smaller than planets. Hence they are sometimes called minor planets.
Asterism: An asterism is an easily recognized pattern of stars usually part of a bigger constellation. A well-known example is the Big Dipper asterism, which resembles a plough or dipper, and is part of the constellation Ursa Major. An asterism is not itself a constellation.
AU: An astronomical unit (AU) is a unit of measure approximately the distance between Earth and Sol.
Black Hole: A tiny region of space where gravity is so strong that not even light can manage to escape.
Binary Stars: A binary star is a star system comprising of two stars orbiting each other.
Cluster: A star cluster is a group of stars, which can range from a few hundred to several thousands or millions of stars. An open star cluster is a cluster of randomly scattered stars. They are not as densely populated as globular clusters and can have different shapes and forms. A globular cluster is a group of tightly packed stars forming a spherical shape. The name is in fact derived from the Latin globulus, meaning small sphere.
Comet: A comet is a celestial body orbiting the Sun that, when close enough to be heated by the Sun’s heat, emits a nebulous envelope called a coma, as a result of released gas and dust, scattered by the Sun’s solar wind. Thus the object appears to have a glowing tail.
Conjunction: A conjunction occurs when 2 or more celestial bodies appear close to each other.
Constellation: A constellation is no more than an arbitrary grouping of [bright] stars. In fact, different civilizations saw different patterns in the sky, thereby having different constellations. Today’s constellations are mainly of Greek origin, with many being named after Greek mythological heroes and creatures, though the Greeks themselves probably borrowed heavily from myths of other civilizations.
Constellations are extremely helpful in guiding us through the universe. 12 "special" constellations form the zodiac.
Crater: A depression in the form of a hollow bowl which results either from a high velocity impact with another object, such as a meteorite, in the case of an impact crater, or, in the case of a volcanic crater, is caused by volcanic activity. The surface of the moon is riddled with craters which are easily visible with binoculars.
Double Stars: A double star refers to a star system made up of two stars which appear to lie together in the sky. The two stars may either be visually linked and only seem to lie together, when in actual fact they may be thousands of light years away- these are called optical doubles - or they may be gravitationally linked and actually orbit each other, as in a binary star system.
Galaxy: A galaxy consists of stars, including planets and other orbiting celestial objects, gas, dust, star clusters and other materials. Our solar system for instance – i.e. the Sun, the Earth and all the other planets and asteroids – forms a tiny part of the Milky Way Galaxy.
Meteor: A meteor is a bright streak of light caused by a small particle of space debris, sometimes no bigger than a grain of sand, as it enters Earth's atmosphere.
Milky Way: The Milky Way is the name given to our galaxy. The name actually refers to the faint hazy white band crossing the sky as seen in dark areas at night, which to the ancients resembled a stream of milk.
Moon: A moon is a celestial body that orbits a planet, and moons are thus sometimes called satellites. Moons vary in sizes, and can be as small as a big asteroid, such as the Martian moon Deimos, or as big as a small planet, like Ganymede, one of Jupiter’s moons, which is bigger than Mercury. The Moon is Earth’s only moon.
Nebula: A nebula is an interstellar cloud of dust or gas in space (the word nebula is in fact Latin for cloud). One of the most famous nebulae seen from Earth is the Great Orion Nebula, found just below the three stars marking Orion’s belt.
Planet: Planets are large celestial bodies that orbit a star. The Earth for instance is a planet that orbits Sol. The Greeks named those stars that seemed to move quickly across the sky "planets", which meant wanderers. Planets are seen from Earth as very shiny stars, though they are easily distinguishable since, unlike stars, they never twinkle. In reality planets do not produce any light of their own, but simply reflect the light of the Sun.
Quasar: A quasar is the bright, active core of a very distant galaxy.
Satellite: A satellite is a small object orbiting a larger one. A satellite can be a natural object, such as a moon or asteroid, or an artificial one, such as a spacecraft.
Sol: Sol is the name given to our Sun.
Solar System: The solar system is a system of celestial bodies made up of the Sun at the centre and other bodies, including planets, moons, comets and asteroids orbiting around it, of which our Earth is part.
Star: A star is a huge gaseous sphere, producing a tremendous amount of heat and energy and visible from earth as a tiny speck of light. Stars are in fact suns and many of them are a lot bigger than our own Sun.
Many of the stars visible from Earth have a proper name, which is usually of Arabic origin, though some have a Latin name. Stars can be referred to by this proper name or by their scientific name, such as that given to them by Johann Bayer, who designated Greek letters to the individual stars of each constellation. For instance, a particular star in the Taurus constellation can be referred to by its proper name Aldebaran, meaning "the follower", or by its Bayer designation, Alpha Tauri.
Sunspot: A sunspot is an area on the Sun’s surface that is darker and cooler than its surrounding area.
Supernova: A supernova is a violent explosion marking the death of a star. A nova is a smaller explosion that can happen repeatedly to the same star for various reasons, and is thus a more frequent phenomenon.
Variable Stars: A variable star is a star whose apparent brightness varies. This may be due to different reasons.
Zodiac: The zodiac is made up of twelve constellations, namely: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, Pisces.