Third quarter Moon on May 22, 2022 | SkyNews
Third quarter Moon on May 22, 2022 (Chris Vaughan, Starry Night Education)

This Week’s Sky: May 16 to 22, 2022

As the Moon reaches third quarter at the end of the week, prepare for dark night skies, great for deep-sky object hunting.

Every week, SkyNews publishes a list of key events in the Canadian sky in This Week’s Sky. This series gives you all the latest news in Solar System movements, including where the planets are in our sky and Moon phases. From eclipses to meteor showers, This Week’s Sky keeps you updated on the best in upcoming astronomical highlights.

Wednesday, May 18 – Mars passes Neptune (pre-dawn)

Mars passes Neptune on May 18, 2022 | SkyNews
Mars passes Neptune on May 18, 2022 (Chris Vaughan, Starry Night Education)

Low in the southeastern sky before dawn on the mornings surrounding Wednesday, May 18, the faster motion of magnitude 0.76 reddish planet Mars will carry it closely past the much fainter blue planet Neptune. They’ll be close enough to share the view in a backyard telescope from May 16 to May 20, with Mars approaching Neptune from celestial west. At closest approach on Wednesday, look for Neptune positioned 32 arc-minutes (slightly more than the Moon’s diameter) to the south of 730 times fainter Neptune. (Your telescope may flip and/or mirror-image the arrangement shown here.) The conjunction will be more easily seen by observers at southerly latitudes, where the planets will sit higher in a darker sky.

Sunday, May 22 – Half Moon meets Saturn (pre-dawn)

Half Moon meets Saturn on May 22, 2022 | SkyNews
Half Moon meets Saturn on May 22, 2022 (Chris Vaughan, Starry Night Education)

In the southeastern sky before dawn on Sunday, May 22, the waning half-illuminated Moon will commence its monthly trip past the bright planets gathered there. On Sunday, Saturn will appear as a yellowish dot shining a slim palm’s width above (or 5 degrees to the celestial north) of the Moon. Mars and the much brighter planets Venus and Jupiter will be arrayed well off to their left (celestial east), making a terrific photo opportunity when composed with some interesting scenery.

Sunday, May 22 – Third quarter Moon (at 18:43 UTC)

Third quarter Moon on May 22, 2022 | SkyNews
Third quarter Moon on May 22, 2022 (Chris Vaughan, Starry Night Education)

The Moon will officially reach its third quarter phase at 2:43 p.m. EDT or 18:43 UTC on Sunday, May 22. At third (or last) quarter the Moon is half-illuminated, on its western, sunward side. It will rise around midnight, and then remain visible until it sets in the western daytime sky in late morning. Third quarter moons are positioned ahead of the Earth in our trip around the Sun. About 3.5 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.

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.

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