SUN 06 JUN 2004 COMMUNITY GoobNet Mailbox

WEEKLY WHINE

Keep your planets safe

Do you live in the Western Hemisphere?

Ha ha!

You'll have to be content with watching Venus's transit across the Sun online. But for those of you in other parts of Earth, you'll be able to perform your own measurement of the distance to the Sun. Or you can just poke a little hole in a sheet of paper and then look at a big circle with a little circle in it.

Whichever method you prefer, you can also annoy others by making stupid observations and hoping that someone else will actually care what you have to say. This is the method preferred by so many of those who fill up the GoobNet Mailbox and make us have to suppress our gag reflexes when we open it.

What's the big deal about a dot in front of the Sun? - Clive Chandler, Regina, SK, Canada

It looks really neat. Duh.

I heard they're going to use new instruments to look at the Sun. How will that work? - Mark Rossi, Vaduz, Liechtenstein

Well, several teams are using imagers that may eventually fly in space on missions like the Terrestrial Planet Finder and Eddington. They'll test them on this transit by trying to observe the light that Venus obscures - less than .01% of the Sun's total light.

.01%? Isn't that only a little bit? - Chase Arnsingphothu, Rangoon, Myanmar

Nah, not really. It's about .14 W/m².

So how come the Venus transits come in eight year pairs spaced out by, like, more than a hundred years? - Anoukh Versalay, Carson City, NV, USA

Just because. Can't you accept that?

I guess, but I thought you were supposed to be, like, smart or something. That's what my cousin's chauffeur's twin's conscience said. - Anoukh Versalay, Carson City, NV, USA

Well, you're misinformed. And a little crazy. Anyway, if you must know why they have such a strange recurrence pattern, I guess we can tell you. The planes of Earth's and Venus's orbits cross where Earth is in December and June. Venus's synodic period with Earth is 583 days. So, when Venus is in the right place to transit the Sun as seen from Earth, it'll be in just about the right place again after eight years - five synodic periods. Then, eight years after that, Venus has moved back to just outside the Sun's relative position. So you have to wait about 75 more synodic periods until the inferior conjunctions are at the node crossings again.

What? - Carla Tombaugh, Bradford, IL, USA

We're not going to explain it again.

So how's it different from the Mercury transit last year? - Harris Fenderson, Wellington, New Zealand

It'll look cooler. Besides, you'll actually be able to detect Venus's atmosphere.

Look out! This transit will dim the Sun so much that a new ice age will start! Civilisation as we know it is doomed! - Rolf Cho, Auxerre, France

Shut up.