At-a-glance weekly updates about the sky to help you plan your observing moments.
Tuesday, May 9 – Venus nears the Shoe-Buckle Cluster (evening)
For several nights surrounding Tuesday, May 9, the orbital motion of the very bright planet Venus will carry it past the large open star cluster in Gemini known as Messier 35 or the Shoe-Buckle Cluster.
Starting on May 4, the planet and the cluster will become close enough to share the view in binoculars (orange circle), with M35 sparkling to Venus’ upper left (or celestial east-southeast).
At their closest approach on May 9, the cluster will be positioned just a thumb’s width to the lower left (or 1.8 degrees south) of Venus. That will be close enough to see them together in a backyard telescope. But you may need to hide bright Venus just out of view to better see the patch of stars, which covers an area the size of the Moon.
After Tuesday, Venus will climb away from the cluster, but the pair will continue to share binoculars until May 13.
Friday, May 12 – Third quarter Moon (at 14:28 GMT)
The Moon will officially reach its third quarter phase at 10:28 a.m. EDT, 7:28 a.m. PDT, or 14:28 GMT on Friday, May 12.
At third (or last) quarter, the Moon appears half-illuminated, on its western, sunward side. It will rise in the middle of the night, and then remain visible until it sets in the western daytime sky during late morning.
Third quarter Moons are positioned ahead of the Earth in our trip around the Sun. About three and a half hours later, Earth will occupy that same location in space. The week of dark, moonless evening skies that follow this phase are the best ones for observing deep sky targets.
Saturday, May 13 – Saturn shines near the Moon (pre-dawn)
Early risers on Saturday morning, May 13, can see the waning crescent Moon shining prettily in the southeastern sky.
The prominent yellowish dot of Saturn will appear a slim palm’s width to the Moon’s upper left (or five degrees to the celestial north) from the time they clear the treetops — at around 3 a.m. local time, until the brightening sky hides Saturn.
For observers in more westerly time zones, the Moon will have shifted a little closer to Saturn, allowing them to share the view in binoculars (orange circle). On the following morning, the Moon will move east and shine to Saturn’s lower left.
Saturday, May 13 – Ceres stands still (all night)
On Saturday, May 13, the minor planet Ceres (the largest object in the main asteroid belt) will cease its motion across the background stars, completing a westerly retrograde loop that it began in February (red path with dates).
Tonight, the magnitude 7.9 object, which is visible in binoculars (orange circle) and backyard telescopes, will be located on the border between Coma Berenices and Leo, two finger widths to the left (or two degrees to the celestial east) of the bright star Denebola. After tonight, Ceres will drop into Virgo and gradually resume its regular eastward motion.
Chris Vaughan is a senior astronomer and earth scientist at AstroGeo.ca. He writes Astronomy Skylights, and is the co-author of “110 Things to See With a Telescope.”