Diagram of the third quarter Moon on April 4, 2021. | SkyNews Magazine

This Week’s Sky: March 29 to April 4, 2021

The zodiacal light returns, and the Moon wanes to its third quarter.

Tuesday, March 30 – Zodiacal light (after dusk)

Diagram of the zodiacal light on March 30, 2021. | SkyNews Magazine
Zodiacal light (Chris Vaughan, Starry Night Education)

At the end of March, we receive another opportunity to view the zodiacal light. Best seen in a location where the sky is free of light pollution, after the evening twilight has disappeared you’ll have about half an hour to check the western sky for a broad wedge of faint light extending upwards from the horizon and centred on the Ecliptic (i.e., below Mars). The viewing period will end with the new Moon on April 11.

Read Elizabeth Howell’s article for more on the zodiacal light.

Friday, April 2 – Mars passes NGC 1746 (evening)

Diagram of Mars passing NGC 1746 on April 2, 2021. | SkyNews Magazine
Mars passes NGC 1746 (Chris Vaughan, Starry Night Education)

In the western sky on Friday evening, April 2, the orbital motion of reddish Mars (red path with labeled dates:time) will carry it closely past a large open star cluster designated NGC 1746. That cluster sits between the horns of Taurus, the Bull. The planet will be close enough to the star cluster to see them together in binoculars on the surrounding evenings. At closest approach on Friday, Mars will be positioned just to the upper right (or to the celestial north) of the cluster’s edge, allowing the pair to be viewed at the same time in a backyard telescope (red circle). (Note that your telescope might flip and/or mirror-image the binoculars’ orientation shown here.)

Sunday, April 4 – Third quarter Moon (at 10:02 GMT)

The Moon will officially reach its third quarter phase at 6:02 a.m. EDT (or 1:30 GMT) on Sunday, April 4. At third quarter, our natural satellite always rises in the middle of the night and remains visible in the southern sky all morning. The Moon will appear half-illuminated on its western side, toward the pre-dawn Sun. 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 ensuing week of moonless evening skies will be ideal 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.