24 Jan 2011
Part of the challenge - and fun - of making a "hard" science like astronomy more accessible to normal humans comes in trying to dispel some commonly held misbeliefs. Here is a small order of those beliefs with a side of corrections.
1. There is no gravity in space.
When most of us think of space we think of things floating around everywhere in random directions, unshackled by gravity. Not true. There is gravity literally everywhere. Here's why.
Anything that has mass - that is, anything made of stuff - has gravity. Stars, planets, elephants, poodles, you and me; we all have gravity, however minuscule, and exert a gravitational pull on things around us.
Moreover, that gravity never drops to zero. It decreases with distance, to be sure, but never really goes away. So no matter where you go in the universe, things are tugging on you, even in the deepest parts of empty space.
2. The Big Dipper is a constellation.
The Big Dipper is not a constellation, it is an asterism. A constellation is an assemblage of stars, most often handed down from antiquity, designating a particular part of the sky in honor of a mythical god or creature. True, they rarely look like the creature or object they are named for, but they are not really meant to.
But there some starry sets in the skies, sprinkled amongst those constellations, which actually look like things, and are screaming out for special recognition. They are called asterisms. There is a "Great Square" in Pegasus, the "Northern Cross" in Cygnus, and the giant "W" in Cassiopeia. And of course within The Great Bear, Ursa Major, is a set of stars which looks remarkably like a dipper, and a big one at that. Hence the asterism known as the "Big Dipper."
3. Our sun has been here since the Beginning of it all.
Astronomers have placed the creation of the universe at about 13.7 billion years ago, but all the evidence puts our own star on the scene at only about 5 billion years ago. Normally this is just dry trivia, but the beauty of it is that our star formed at just the right time.
The sun was born when there was still plenty of hydrogen and helium to make stars, but it was also a time when the galaxy was dusted with just enough of the other heavier elements which were just laying around after billions of years of element-spewing supernovae explosions. This almost assured that the new star would have stuff to make planets. This also assured building blocks for life.
This could not have happened earlier in the universe. Our star is the perfect age, born at the perfect time for planets - and us - to be here.
Three more myths down the drain. There will be more this year. Stay tuned.
10 Jan 2011
Clear night skies in January are beautiful; there are long hours of darkness and plenty of stunning sites to see. But it can also get cold and cloudy and rainy.
Let's assume, for the sake of the true observers here, that we will have the time - and the skies - this month to go out and take a look. Here are some things to keep an eye out for.
First, you may notice just after sunset a bright object in the southwestern skies. That would be Jupiter. But wasn't that Jupiter in the eastern skies during late summer? What's it doing over there in the west now?
We have passed quickly by it in our short orbit these last months. The giant, plodding planet is now almost 500 million miles away and, from our perspective, soon to move behind the sun. But fear not! Before long the King of Planets will be on the other side of the sun, and instead of following it down after sunset, will be leading our star as it rises in the morning. Jupiter will re-emerge predawn in May, joining Venus as a fellow "morning star."
This may be a good week for you to keep an eye on our Moon. It will start off tonight near First Quarter, above your head at sunset, with Jupiter a little to the west of it.
If you have a telescope or even binoculars, see for yourself why amateur astronomers love this phase so much. The sun's light hits it from such an oblique angle that the shadows of the craters up there are intense and make observing the surface almost a 3D experience.
Watch over the next nights as the moon traverses in its orbit towards the east, finally reaching full moon status on the 19th.
And of course there are the winter stars. No need for a telescope here. Just go out and enjoy them. The big name of the winter playlist, arguably, is Orion, that monster of a hunter rising in the east after sunset.
This would be a great time to download a free star chart of the winter skies off the internet and start observing. See if you can spot the stars Betelgeuse and Rigel in Orion, or his Belt and the Great Nebula. Find the constellations Taurus and Canis Major, Orion's neighbors on either side. Track down within them the stars Aldeberan and Sirius, and the star cluster, The Pleiades.
These are great skies for observing. Start off this new year with your own observation sessions. And bring family and friends!