A diagram of the New Moon on September 6, 2021. | SkyNews
New Moon on September 6, 2021 (Chris Vaughan, Starry Night Education)

This Week’s Sky: September 6 to 12, 2021

With the new Moon early this week, check out some deep-sky targets and the zodiacal light.

Monday, September 6 – New Moon (at 8:51 p.m. EDT)

A diagram of the New Moon on September 6, 2021. | SkyNews
New Moon on September 6, 2021 (Chris Vaughan, Starry Night Education)

The Moon will reach its new phase on Monday, September 6 at 8:51 p.m. EDT. (That corresponds to 0:51 GMT on Tuesday, September 7.) 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 unobservable from anywhere on Earth for about a day (except during a solar eclipse). After the new Moon phase Earth’s planetary partner will return to shine in the western sky after sunset.

Tuesday, September 7 – Morning zodiacal light for mid-northern observers (pre-dawn)

A diagram of the morning zodiacal light for mid-northern observers. | SkyNews
Morning zodiacal light for mid-northern observers (Chris Vaughan, Starry Night Education)

For about half an hour before dawn during moonless periods in September and October annually, the steep morning ecliptic favours the appearance of the zodiacal light in the eastern sky for observers in mid-northern latitudes around the world. Zodiacal light is sunlight scattered by interplanetary particles concentrated in the plane of the solar system. It is more readily seen in areas free of urban light pollution. During the two-week period from now until the full Moon on September 20, look just above the eastern horizon for a broad wedge of faint light rising from the horizon and centered on the ecliptic (marked by green line). It will be brightest to the left of the bright star Procyon. Don’t confuse the zodiacal light with the Milky Way, which is positioned nearby in the southeastern sky.

Wednesday, September 8 – Crescent Moon above Mercury (after sunset)

A diagram of the crescent Moon above Mercury on September 8, 2021. | SkyNews
Crescent Moon above Mercury on September 8, 2021. (Chris Vaughan, Starry Night Education)

Look low in the western sky for a brief period after sunset on Wednesday, September 8 to see the very young crescent Moon (only 4.8-per-cent illuminated) positioned a slim palm’s width to the upper right (or 5 degrees to the celestial north) of Mercury. The magnitude 0.0 planet will become apparent as the sky darkens beyond 7:30 p.m. local time and will set 30 minutes later. The Moon will take an additional half hour to set. This conjunction will be a challenge to see from mid-northern latitudes, but quite easy from southerly locations. Use binoculars (red circle) only after the sun has completely set.

Thursday, September 9 – Young Moon between Venus and Vesta (after sunset)

A diagram of the Young Moon between Venus and Vesta on September 9, 2021. | SkyNews
Young Moon between Venus and Vesta on September 9, 2021. (Chris Vaughan, Starry Night Education)

In the west-southwestern sky after sunset on Thursday, September 9, look for the young crescent Moon shining several finger widths to the upper right (or 4 degrees to the celestial northwest) of the bright planet Venus. The main belt asteroid designated (4) Vesta will be there, too – positioned about double the Moon’s distance from Venus. The magnitude 7.7 asteroid will be somewhat difficult to see unless you are viewing it from a southerly latitude, where skies darken quickly after sunset. Tonight, use binoculars (red circle) to hunt for Vesta only a Moon’s diameter above the medium-bright star 80 Virginis. The Moon will dance away from them after Thursday, but Venus and Vesta will continue to travel eastward together through the stars of Virgo. Compare their positions with Virgo’s bright star Spica.

Saturday, September 11 – Asteroid Pallas at opposition (all night)

A diagram of Asteroid Pallas at opposition on September 11, 2021.  | SkyNews
Asteroid Pallas at opposition on September 11, 2021. (Chris Vaughan, Starry Night Education)

On Saturday, September 11, the main belt asteroid designated (2) Pallas will reach opposition and its minimum distance from Earth for this year. On the nights near opposition, Pallas will rise at sunset and set at sunrise, and shine with a peak visual magnitude of 8.55. That’s within reach of backyard telescopes, but wait until the asteroid has risen higher for the best view of it – about 9 p.m. local time or later. Pallas will be situated in western Pisces, several finger widths to the right (or 4 degrees to the celestial southwest) of the medium-bright star Gamma Piscium. Nearby Neptune will reach its own opposition several days from tonight.

Sunday, September 12 – Half-Moon above Antares (evening)

A diagram of the half Moon above Antares on September 12, 2021. | SkyNews
Half Moon above Antares on September 12, 2021. (Chris Vaughan, Starry Night Education)

Look low in the southwestern sky on Sunday evening, September 12, for the waxing, nearly half-illuminated Moon shining several finger widths to the upper right (or 3 degrees to the celestial north) of Scorpius’ very bright, reddish star Antares, the “Rival of Mars”. The duo will share the field of view in binoculars (red circle). Off to their right (west), try and spot the will vertical row of scorpion’s fainter white claw stars Graffias, Dschubba, and Pi Scorpii. Grab a photo of the pretty scene as soon as it gets dark. That part of the sky will set after 10 p.m. local time.

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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