October 23, 2017

Your Chance to see the “Moons”(?) of Venus!

Two degree FOV on January 13th… north is up.

(Created by the Author in Starry Night).

The planet Venus is going through some pretty fancy sky maneuvering this year. Starting off low to the south in dusk skies, it is about to shoot dramatically to high northerly declinations later this spring, and then dip down to a climatic transit of the Sun on June 5th-6th this summer. This will be a once in our life-time event, unless you’re laying plans to have your head preserved or down-load your consciousness ‘til the next transit of our sister world in 2117. But this week, I’d like to point out a close conjunction that will use the brilliancy of Venus to guide you to another world that many have never seen.

We’re talking about the close conjunction of Venus with the planet Neptune on January 13th.  Closest apparent passage of the two occurs at 07:00 AM UTC, when the two are just shy of over a degree apart. North American viewers will get a good shot at the pair on the evenings of January 13th and 14th, as Venus lies about 25-35° degrees above the western horizon at sunset and doesn’t set for another 2.5 to 3 hours after the Sun for observers at mid-northern latitudes. Do you spy a bright +4th magnitude star to the south of Venus on the same date? That’s none other than Iota Aquarii. Together, the grouping might just take on the appearance of the system of moons that Venus never had. Use a low power field yielding one degree in diameter to sweep up the dusk three-some, and then plop in the magnification to nab Neptune’s tiny grey-blue disk versus Iota Aquarii’s pinpoint appearance. Neptune heads towards superior conjunction on the far side of the Sun on 19th of February and this will be most likely your last chance this season to nab it!

Did you know that Venus was once thought to have a large moon? It’s true; we’ve written about the spurious moon named Neith (as in the astronomers that say “Neith?” a bit of Monty Python humor) recorded from the time of Giovanni Cassini in 1672 almost right up until 1900 or so. Such “sightings” were almost certainly internal optical reflections or close conjunctions with nearby bright stars; Venus itself can be dazzling in appearance when seen through the eyepiece. It’s even been proposed by researchers that Cassini might have seen an object transiting the inner solar system, but this too seems unlikely. The Moon of Venus was described as having a phase resembling Venus in the same orientation, but even the “quasi-moon” of Venus, an asteroid known as 2002 VE68, is in a wide resonant orbit and is far to tiny. Whatever the case, it’s fascinating to follow our nearest world through its daily motion across the starry background and wonder just what those astronomers of yore saw, long ago.

Also, don’t miss out on the Full Wolf Moon of January, occurring on the 9th at 2:30 AM EST/7:30AM UTC. Also known as the Moon after Yule, the Wolf Moon was named as such by the Algonquin Indians for the wolves which would howl through the long winter’s night. This is the first Full Moon of the year, and the 3rd most northern (missing by less than a degree at Full with a declination of 19° 04’ North), causing to ride high in the sky for the entirety of the cold, January night.

Comments

  1. steve says:

    far TOO tiny.

  2. David Dickinson says:

    It’ll be a tough grab, for sure, but bright Venus will make a good “guidepost” for folks with a telescope to at least spy the tiny speck of Neptune, an object that many have never seen…

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