Tuesday, May 11 – New Moon (at 19:00 GMT)
The Moon will officially reach its new phase on Tuesday, May 11 at 3:00 p.m. EDT (or 12:00 p.m. PDT or 19:00 Greenwich Mean Time). While new, the Moon is travelling between Earth and the Sun. Since sunlight can only reach the far side of the Moon, and the Moon is in the same region of the sky as the Sun, the Moon becomes completely hidden from view from anywhere on Earth for about a day. After the new Moon phase Earth’s celestial night-light will return to shine in the western evening sky.
Wednesday, May 12 – Crescent Moon kisses Venus (after sunset)
Low in the west-northwestern sky after sunset on Wednesday, May 12, the young crescent Moon will be positioned a finger’s width to the lower left (or 1 degree to the celestial south) of Venus. The very bright planet will be easier to find first as the sky darkens after about 8 p.m. local time. Be sure that the Sun has completely set before using binoculars or a telescope (red circle) to view the duo. Observers in much of New Zealand, Eastern Polynesia, and Easter Island can see the Moon occult Venus in the mid-day sky.
Thursday, May 13 – Crescent Moon near Mercury (after sunset)
A day after passing Venus, the crescent Moon will climb to sit several finger widths to the left (or 3 degrees to the celestial southeast) of Mercury in the west-northwestern sky of Thursday, May 13. The pair will set at about 10 p.m. local time, well after sunset, allowing them to shine in a darkened sky. The Moon and the planet will fit together in the field of view of binoculars (red circle). Bright Venus will shine below them.
Saturday, May 15 – Crescent Moon and Mars (evening)
In the western sky after dusk on Saturday, May 15, the pretty, waxing crescent Moon will shine several finger widths to the lower right (or two degrees to the celestial northwest) of the reddish planet Mars. The duo will appear together in binoculars (red circle). The Moon’s orbital motion will carry it closer to Mars by the time they set together shortly before midnight local time.
Sunday, May 16 – Moon occults bright star Kappa Geminorum (early evening)
On Sunday evening, May 16, observers in the eastern continental United States and Canada can watch the waxing Moon occult the medium-bright star Kappa Geminorum (or κ Gem). The dark leading edge of the Moon will cover the star first, causing its point of light to wink out. The star will re-appear from behind the bright eastern limb of the Moon some time later. Ingress and egress times vary by latitude – so use Starry Night or another astronomy app to look up the times where you live. In New York City, Kappa Geminorum will disappear at 9:37 p.m. EDT and re-appear at 10:39 p.m. EDT. Wherever you are observing from, start watching a few minutes before the appointed times. The event will be visible in binoculars and backyard telescopes, but remember that a telescope (red circle) will likely invert and/or mirror the scene shown here.
Sunday, May 16 – Mercury at greatest eastern elongation (after sunset)
In the west-northwestern sky on the evening of Sunday, May 16, Mercury (orbit shown in red) will be hours from its widest separation, 22 degrees east of the Sun. With Mercury positioned above (north of) the evening ecliptic (green line), this appearance of the planet will offer excellent views for Northern Hemisphere observers, but not so for observers in the Southern Hemisphere. The optimal viewing period at mid-northern latitudes will be 8:30 to 9:30 p.m. local time. Viewed in a telescope (inset) the planet will exhibit a waning, half-illuminated phase.
Chris Vaughan is a science writer, geophysicist, astronomer, planetary scientist and an “outreach RASCal.” He writes Astronomy Skylights, and you can follow him on Twitter at @astrogeoguy. He can also bring his Digital Starlab portable inflatable planetarium to your school or other daytime or evening event. Contact him through AstroGeo.ca to tour the universe together.