Sun to Outshine Spectacular Cosmic Alignment Saturday

[Buster's Uncle]

Sun to Outshine Spectacular Cosmic Alignment Saturday
SPACE.COM
by Geoff Gaherty, Starry Night Education | November 21, 2014 10:40am ET



On Saturday morning, Nov. 22, there will be a spectacular gathering of the sun, the moon, three planets and a dwarf planet, all within a 20-degree span of sky. Unfortunately, most observers on Earth will be able to see it. Credit: Starry Night software



The morning sky will play host to a spectacular gathering of solar system objects grouped closely together tomorrow (Nov. 22), but it won't be easy for observers on Earth to see it.

The sun, moon, three planets and the dwarf planet Ceres will all appear within a 20-degree span of sky. (For reference, your clenched fist held up to the sky measures about 10 degrees across.) Mercury and Saturn will be just west of the sun and new moon, while Venus and Ceres will be to the east. Unfortunately, the bright sun will wash out the beautiful "conjunction," but interested observers can still use a planetarium software program like Starry Night to check out the stunning event.

Because the moon and three of the five naked-eye planets are gathered close to the sun, there is currently a remarkable absence of bright planets in the night sky. Mars is getting close to the sun, and sets around 8 p.m., and Jupiter is in the morning sky, rising around 11 p.m.

Conjunctions (groupings of astronomical objects from Earth's perspective) between two astronomical bodies occur all the time. The sun, moon and planets all move in orbits close to the same plane, which is called the ecliptic. It gets its name from the fact that when the moon passes in front of the sun or when Earth's shadow falls on the moon, an eclipse occurs.

Of all objects in Earth's sky, the moon appears to move the fastest, completing its journey around the Earth in just under a month. Measured against the sun, the moon repeats its phases every 29.4 days, while measured against the stars, it takes 27.3 days. The difference is accounted for by the amount the Earth moves in a month.

So the moon is in conjunction with the sun once every 29.4 days, an event called the new moon. This month's new moon occurs tomorrow at 7:32 a.m. EST (0032 Nov. 23 GMT).

Most of the time, observers can't see a new moon — for two reasons. First, it is too close to the brilliant sun. Second, the side of the moon that faces Earth during a new moon is completely in shadow, because the sun is lighting the moon's far side. The only exceptions are the rare occasions when the moon passes directly in front of the sun, causing a solar eclipse, as happened last month. Then the moon appears in silhouette against the sun.

Editor's Note: If you have an amazing skywatching photo you'd like to share for a possible story or image gallery, please contact managing editor Tariq Malik at spacephotos@space.com.


http://www.space.com/27837-planet-conjunction-saturday-skywatching.html

[Geo]

Funny that. People could mistake Saturn for Mercury in the morning glow then.

[Buster's Uncle]

Saturn's not nearly as bright, is it?

[Geo]

Saturn's not nearly as bright, is it?

Saturn's usually has quite a bit brighter magnitude then Mercury. That's why, if one spots a dim star in the morning glare, might think Mercury is in view.
I probably had the same a couple months ago with Jupiter. The planet had passed the Sun the week before or so, and Mercury was in the same region of the sky. What I thought was Mercury was most likely Jupiter.

List of planetary magnitude ranges: http://nl.wikipedia.org/wiki/Magnitude#Tabel_van_schijnbare_magnitudes_in_het_zonnestelsel