First quarter Moon on April 9, 2022 | SkyNews
First quarter Moon on April 9, 2022 (Chris Vaughan, Starry Night Education)

This Week’s Sky: April 4 to 10, 2022

The Moon waxes to its first quarter this week, with the crescent passing Ceres in Taurus.

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.

Tuesday, April 5 – Crescent Moon and Ceres in Taurus (early evening)

Crescent Moon and Ceres in Taurus on April 5, 2022
Crescent Moon and Ceres in Taurus on April 5, 2022 (Chris Vaughan, Starry Night Education)

In the western sky on Tuesday evening, April 5, the waxing crescent Moon will shine among the stars of Taurus, the Bull. The prominent Pleiades star cluster will be positioned a fist’s width to the Moon’s lower right (or celestial west), and the bright, orange-tinted star Aldebaran will shine a palm’s width to the Moon’s lower left (celestial south). For observers in the Americas that night, the dwarf planet (formerly asteroid) designated (1) Ceres will be located nearly a palm’s width above the Moon (or 5 degrees to its east). About 10 hours later, observers in the region around Thailand and Singapore can see the Moon occult Ceres.

Friday, April 8 – Lunar X (peaks at 22:00 UTC)

Lunar X on April 8, 2022
Lunar X on April 8, 2022 (Chris Vaughan, Starry Night Education)

Several times a year, for a few hours near its first quarter phase, a feature on the Moon called the Lunar X becomes visible in strong binoculars and backyard telescopes. When the rims of the craters Purbach, la Caille, and Blanchinus are illuminated from a particular angle of sunlight, they form a small, bright X-shaped pattern. The Lunar X is located on the terminator, about one third of the way from the southern pole of the Moon, at lunar coordinates 2° East, 24° South. On Friday, April 8, the Lunar X will appear while the Moon is shining in a daylit sky in Canada and the rest of the Americas. For observers in Europe and western Africa, the Lunar X is predicted to start developing by about 9 p.m. British Summer Time (or 20:00 UTC), peak in intensity around 11 p.m. BST (or 22:00 UTC), and then gradually fade out during the following 90 minutes. At the same time, watch for a Lunar V along the northern span of the terminator near the crater Ukert. The Lunar X and V will be visible anywhere on Earth where the Moon is shining between 20:00 UTC on April 8 and 00:00 UTC on April 9.

Saturday, April 9 – First quarter Moon (at 06:48 UTC)

First quarter Moon on April 9, 2022 | SkyNews
First quarter Moon on April 9, 2022 (Chris Vaughan, Starry Night Education)

When the Moon completes the first quarter of its orbit around Earth at 2:48 a.m. EDT (or 06:48 UTC) on Saturday, April 9, the relative positions of the Earth, Sun and Moon will cause us to see our natural satellite half-illuminated on its eastern side. While at first quarter, the Moon always rises around noon and sets around midnight, allowing it to be seen in the afternoon daytime sky, too. The evenings surrounding first quarter are the best ones for viewing the lunar terrain when it is dramatically lit by low-angled sunlight.

Sunday, April 10 – The Lunar Straight Wall (evening)

The Lunar Straight Wall on April 10, 2022 | SkyNews
The Lunar Straight Wall on April 10, 2022 (Chris Vaughan, Starry Night Education)

On Sunday evening, April 10, the pole-to-pole terminator that divides the lit and dark hemispheres of the waxing gibbous Moon, will fall to the left (or lunar west) of Rupes Recta, also known as the Lunar Straight Wall. The rupes, Latin for “cliff,” is a north-south aligned fault scarp that extends for 65 miles (110 kilometres) across the southeastern part of Mare Nubium, which sits in the lower third of the Moon’s Earth-facing hemisphere. The wall is visible in good binoculars and backyard telescopes. It is most prominent a day or two after first quarter, and also on the days before last quarter. For reference, the very bright crater Tycho is located due south of the Straight Wall.

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 to tour the Universe together.