A diagram showing the Moon passing Mars, April 16, 2021. | SkyNews
Moon passes Mars (Chris Vaughan, Starry Night Education)

This Week’s Sky: April 12 to 18, 2021

The waxing crescent Moon is the “star” of the week, passing by Taurus, Mars and Messier 35.

Tuesday, April 13 – Asteroid Juno stands still near star Mu Oph (midnight to dawn)

A graphic showing Asteroid Juno standing still near star Mu Oph. | SkyNews
Asteroid Juno stands still near star Mu Oph, midnight to dawn (Chris Vaughan, Starry Night Education)

On Tuesday, April 13, the main belt asteroid designated (3) Juno will cease its regular eastward motion across the distant stars of Ophiuchus and begin a westward retrograde loop that will last until early August. On this night, the faint, magnitude 10.8 asteroid will rise just before midnight and then remain visible until the pre-dawn while it crosses the sky less than a finger’s width from the medium-bright star Mu Ophiuchi (μ Oph). Use that star to locate and view the asteroid in your telescope (inset).

Thursday, April 15 – Young Moon and the Bull’s Eye (evening)

A diagram showing the Young Moon and the Bull’s Eye, April 15, 2021. | SkyNews
Young Moon and the Bull’s Eye (Chris Vaughan, Starry Night Education)

In the lower third of the western sky after dusk on Thursday, April 15, the crescent of the young Moon will shine just a few finger widths to the right (or celestial north) of the bright, orange star Aldebaran, which marks the southerly eye of Taurus, the Bull. Use binoculars (red circle) to see the V-shaped group of dimmer stars in the Hyades Cluster. Those stars, which form the bull’s face, are sprinkled downwards and to the right (or celestial northwest) of Aldebaran. The bull’s northerly eye is marked by the medium-bright star Ain, or Epsilon Tauri, which will be positioned between Aldebaran and the Moon.

Friday, April 16 – Moon passes Mars (evening)

A diagram showing the Moon passing Mars, April 16, 2021. | SkyNews
Moon passes Mars (Chris Vaughan, Starry Night Education)

In the western sky after dusk on Friday, April 16, the waxing crescent Moon will be positioned a palm’s width below (or six degrees to the celestial west) of the reddish dot of Mars. The following evening, the Moon’s orbital motion will shift it a similar distance to Mars’ upper left. In the interim, observers in most of central and eastern Africa, the southern parts of the Middle East, India, Southeast Asia, Indonesia, and most of the Philippines can see the Moon pass in front of (or occult) Mars.

Saturday, April 17 – Moon near Messier 35 (late evening)

A diagram showing the Moon near Messier 35, April 17, 2021. | SkyNews
Moon near Messier 35 (Chris Vaughan, Starry Night Education)

Once the sky has darkened after sunset on Saturday, April 17, train your binoculars (red circle) on the waxing crescent Moon and look for a dense clump of dim stars sitting just to the Moon’s lower left (or celestial south). That open star cluster in Gemini is known as Messier 35 or the Shoe-Buckle Cluster. A curved line of bright stars named Tejat, Propus, and 1 Geminorum, which form Castor’s foot, can help you find Messier 35 on a subsequent moonless evening.

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.

Get a Free Digital Issue