Friday, March 09, 2007

A Tale Of Two Worlds

"Just how many planets are in the sky right now?"

That's a question I've heard time and time again. That is actually a complicated question that has a few answers. The truth is that they are all in the sky... the question really comes down to which ones can you see?
Fortunately for us, there are two fine examples visible right now after sunset, Venus in the west and Saturn in the east. Both are glorious in their own right, with brilliant Venus heading towards elongation (its highest point in the western sky, which it will reach on June 9th) and golden Saturn sitting in Leo, not too far from the bright star Regulus (but far out shining it).

The First Star I see Tonight... Isn't...

(image courtesy of "Your Sky")

A star, that is. Even before the last traces of sunlight fade in the west, Venus blazes, very much like that ephemeral "diamond in the sky". Wait until approximately 7pm ET (8pm EDT) to get a good idea of why this planet is frequently mistaken for airplane landing lights (or a UFO!); it is extremely bright, rivaling only the Moon in the night sky. Right now, as viewed telescopically from Terra Firma, it looks for all the world like a gibbous moon. In fact, when viewed from Earth, Venus goes through phases. This is what Galileo discovered in 1610 (both Mercury and Venus appear to go through phases; however Venus is by far the easiest to observe. You need a pretty good telescope to observe Mercury's phases). When Galileo made his observations of Venus, he confirmed the Copernican model of the Solar System to be correct, that the planets orbit the Sun.

(image courtesy IMSS - Firenze)

Even with a modest telescope, you can observe these phases. However, they will not be truly startling until after maximum elongation (again, June 9th), when it will cease to be even and ellipsoid and start to go through quarter and crescent phases. Not only will the phases be more dramatic, Venus will appear larger, since this portion of its orbit rakes it closer to our Earth. For now, Venus should appear as a small, albeit lopsided, disk. It is best viewed with at least 50 magnification in order to show even this (more on that, but next...).

The Lord Of The Rings

Well, I'm pretty sure that that particular label has been applied to Saturn perhaps too often, but was once applied to yours truly in an article in the Palm Beach Post way back in December 2001.

(image courtesy Palm Beach Post)

But this is about the planet Saturn and not me. So much has already been written about Saturn already but I feel that there is always room for more. Saturn is simply amazing these spring evenings. It passed opposition (when it lies opposite the Sun in our skies, effectively coming up at sunset) on February 10th, at which point it was at this orbit's closest approach. So, it is still relatively nearer to us at this time than it normally is.

(image courtesy of "Your Sky")

It is important to remember, though, that the planet Saturn is already 9 times larger than Venus (and its near size twin Earth) and lies over ten times more distant. Its rings span out over twice the planets diameter as well. What does this mean to us here on Earth?
Basically, it means that even a modest telescope with as low as 20 magnification shows Saturn as more than just a disk; it looks like a grain of rice at low power, and 50x and above show the true majesty of the ring system.
This is a great time for observing both planets, but as summer rolls along and Venus begins its descent back into the sunset, the skies will become even more wonderful as Saturn joins it in the west for a celestial rendezvous. Stay tuned!

The Vagabond will be setting up at Ed Austin Regional Park off of McCormick Road at 7pm on March 13th, near the western most parking lots. While light pollution will no doubt be a problem, we will be looking at two fairly bright objects. A little further afield and later in the week NEFAS and my fellow members will be out at Osceola National Park on the night of the 17th as well.

Hope to see you soon.