October 20, 2017

AstroEvent(s): A Week of Moons, Tri-Conjunctions, & Lunar Features!

Venus, Vesta, & Pluto in a 5 degree field of view. (Created by Author in Starry Night).

This week offers a grab bag of unique events, far from the humdrum wide conjunctions and difficult to see pairings. The action starts on February 8th with a rare chance to see Saturn’s moons in 1 -8 order. This occurs in a narrow window from 19:01-19:38 UT, and thus favors the Asian Far East. The planet currently rises around 11PM local, and a majority of the moons should still be in order from your corresponding latitude. The moons range from easy to spot (Titan at magnitude +8.4) to difficult (Mimas at +12.9)… how many can you see? Other Saturn moon alignments for 2011 are:

 1 to 6 JUN 10 2115 to 2300UT

 1 to 7 AUG 2145 to AUG 19 0245UT

 1 to 8 DEC 23 0656 to 0906UT

Our usual thanks goes out to reader and veteran sky calculator Ed Kotapish for passing these along.

Next up is an unusual tri-conjunction in the morning skies. This will give you the chance to spot two difficult targets, using bright Venus as an anchor. On February 9th, there is a chance to see Venus pass within 0.4 degrees of the asteroid Vesta. Venus shines at a dazzling -4.1, while Vesta is at a faint +7.9 magnitude. But wait, there’s more. About 2.3 degrees to the east is faint Pluto at about magnitude +14, tough but not impossible. The whole group is currently very near the globular cluster M22, about 2.8 degrees to the lower right of Venus. Can you catch them all? It would be an interesting photo op… although brilliant Venus may have to be masked for a composite exposure.

Finally, on February 11th, the First Quarter moon skirts within 2 degrees of the Pleiades, again another good photo op. this is prime time to search out the Lunar Straight Wall, a prominent feature in the Mare Nubium… quite week!        

The astro-word for this week is Vestoid. This is a class of asteroids that show a strong absorption band around 1µm, defining a V-type asteroid with considerably more pyroxene than the S-type, another class of stony iron chondrites. Several other Vestoid type asteroids are known, and this class also holds the distinction of one of the only asteroid types that we have actually matched samples to here on Earth. It is strongly suspected that Vesta has sustained a massive impact somewhere in the recent past, and this is the cause of the prevalence of Vesta-like material that exists in the inner solar system. The Dawn spacecraft may reveal some of the asteroids’ secrets as it enters orbit around Vesta this summer for our first good close up look at the asteroid. Vesta is one of the few asteroids that occasionally gets bright enough to spy with the naked eye under dark skies, and may shed light on the mysteries of the solar system.  


  1. [...] This post was mentioned on Twitter by David Dickinson, David Dickinson and David Dickinson, Nick Howes. Nick Howes said: RT @Astroguyz: Tomorrow AM: Venus in conjunction with the asteroid Vesta (and Pluto) 0.4 and 2.3 degrees, respectively: http://bit.ly/gJM39t [...]

Speak Your Mind