By CLIVE JACKSON [email protected]
Clive Jackson is the Director of the Astronomical Observatory of Tavira (Sitio do Malhão, Tavira) and the Camera Obscura (next to the Castle in Tavira), specialising in education and public outreach.
First of all it is best to find dark skies. You’ll always see more if you can get away from light pollution. Even streetlights can detract significantly from the view overhead. As a demonstration, turn-off all the lights and go outside and look up. After about 10 minutes you should count many more stars. This is due to your eyes adjusting to the dim light levels, also called ‘dark adaptation’. Now turn on a light for just a few seconds, and look up one more time. Most of the stars will have vanished, at least until your eyes again adjusted the darkness.
You might want to bring star maps to find your way around. To see those maps in the dark, you’ll want a red-filtered torch. Astronomers use these because red light doesn’t affect your night vision as much as white light does. Binoculars of any size are good to take along too, even if you’re also using a telescope. Not only do they give a nice wide-field view of whatever you might be seeing, but also stargazing with binoculars can be a thoroughly satisfying activity by itself.
Learn some constellations
Astronomy can be enjoyed without any equipment at all; just a bit of patience and imagination can make the night sky interesting. First, you can learn some of the mythology associated with the heavens and also science can help with facts such as the constellation of Scorpius being one of the few that look like its name. Also, the Plough is only a part of a larger constellation, Ursa Major, the Great Bear.
You can use your imagination and join up the dots using the bright stars and making up your own constellations! After all, that’s what ancient sky watchers did long ago, and those are the constellations we see today. An easy way to learn the sky is to use the brighter stars and patterns as pointers to other constellations. For example, the two stars forming the end of the Plough’s bowl point to the right toward Polaris, the North Star. The curved line made by the stars in the Plough’s handle points to an orange coloured star called Arcturus, which means the bear follower in ancient Greek.
Watching meteors shower
April is a good month to spot meteors or ‘shooting stars’ too. In fact, every night of April has a higher than average chance of seeing meteors, and many bright fireballs have been seen during this month. Some have survived their flight through the Earth’s atmosphere and have fallen to the ground as meteorites. This is the name given to any lump of space rock that is found on the Earth’s surface. If you are ever lucky enough to witness the fall of a meteorite, it will most likely be a small black rock weighing less than a kilogram and it will hit the ground at its free fall velocity of around 300mph. This is very slow considering it probably hit our atmosphere at more than 30,000! Our protective air brutally slows meteors down and the energy dissipated is transformed to heat and this causes the bright streak of light in the sky. But the meteorite will only be hot on the outside few millimetres and it would rapidly cool on landing and be covered in frost as the internal temperature would be far below freezing due to the fact that it has spent millions of years floating in space far from the sun.
Some meteorites are considered quite valuable and could be worth more than their own weight in gold! There are people who make a living hunting meteorites – about a thousand fall to Earth every year and this has been going on for millions of years! A meteorite could fall anywhere at any time. It’s not too difficult to find one with patience and care.
The night of April 22 is the peak of the Lyrids meteor shower and the Chinese first recorded this shower in 687 BC.
The Moon was close to Saturn on the night of April 6 in the constellation of Leo.
The Moon was at First Quarter on April 2, full on April 9 and Last Quarter will be on April 17 and New on April 25.
Clive Jackson can be contacted by phone on (00351) 281 321 754, by fax on (00351) 281 324 688, or by email to [email protected]. To visit his website, click on the link to the right of this page.