Lunar libration reveals elusive oceans on Feb. 25, 2023 at 7 p.m. (Chris Vaughan) | SkyNews
Lunar libration reveals elusive oceans on Feb. 25, 2023 at 7 p.m. (Chris Vaughan)

This Week’s Sky: February 20-28

On Saturday, February 25, libration will shift Mare Crisium farther from the Moon’s edge. On the same evening, look closely for two dark patches positioned between Mare Crisium and the Moon’s edge.

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.

Monday, February 20 – New Moon (at 07:06 GMT)

New Moon on Feb. 20, 2023 at 07:06 GMT. (Chris Vaughan) | SkyNews
New Moon on Feb. 20, 2023 at 07:06 GMT. (Chris Vaughan)

At 3:06 a.m. EST, 12:06 a.m. PST or 07:06 GMT on Monday, February 20, the Moon will officially reach its new-Moon phase. At that time it will be located in Aquarius, approximately five degrees south of the Sun. While new, the Moon is traversing the space between Earth and the Sun. Since sunlight is only shining on the far side of a new Moon, and the Moon is in the same region of the sky as the Sun, our natural satellite becomes completely hidden from view for about a day — unless a solar eclipse occurs! This new Moon will arrive only one day after the Moon’s closest approach to Earth this month, generating large tides worldwide. 

Tuesday, February 21 – Earthshine Moon and planets (after sunset)

Earthshine Moon and planets on Feb. 21, 2023 at 6 p.m. (Chris Vaughan) | SkyNews
Earthshine Moon and planets on Feb. 21, 2023 at 6 p.m. (Chris Vaughan)

On Tuesday, February 21, the slender crescent of the young Moon will form a line below Venus and Jupiter — setting up a wonderful wide-field photo opportunity in the western sky after sunset. The Moon, which will be positioned a generous palm’s width below Venus, may exhibit Earthshine. 

Sometimes called the Ashen Glow or the Old Moon in the New Moon’s Arms, the phenomenon is visible within a day or two of the new Moon, when sunlight reflected off Earth and back toward the Moon slightly brightens the unlit portion of the Moon’s Earth-facing hemisphere. 

While it won’t be easily observable when it is that low in the sky, distant Neptune will be lurking several finger widths to the right (or 2.7 degrees to the celestial northwest) of the Moon. 

Wednesday, February 22 – Crescent Moon near Jupiter and Venus (early evening)

Crescent Moon near Jupiter and Venus on Feb. 22, 2023 at 7 p.m. (Chris Vaughan) | SkyNews
Crescent Moon near Jupiter and Venus on Feb. 22, 2023 at 7 p.m. (Chris Vaughan)

The Moon will continue its trip past the bright planets in the western sky on Wednesday evening, February 22. In the hours after sunset, its beautiful slender crescent will shine a thumb’s width to the left (or 1.2 degrees to the celestial south) of Jupiter. Venus will be positioned a palm’s width below them, making another terrific wide-field photo opportunity. The Moon and Jupiter will be cozy enough to share the view in a backyard telescope — allowing you to see a magnified view of our Moon and Jupiter’s moons at the same time. 

Take a photo of them through your eyepiece! As a bonus, the magnitude 8.1 speck of the asteroid Vesta will be observable in a telescope. At around 23:00 GMT, observers in parts of western Antarctica, the Falkland Islands, and southern South America can see the Moon occult Jupiter just before they set in evening. 

Friday, February 24 – Waxing Moon approaches Uranus (evening)

Waxing Moon approaches Uranus on Feb. 24, 2023 at 10:10 p.m. (Chris Vaughan) | SkyNews
Waxing Moon approaches Uranus on Feb. 24, 2023 at 10:10 p.m. (Chris Vaughan)

In the western evening sky on Friday, February 24, the blue-green, magnitude 5.8 speck of Uranus will be positioned a palm’s width above (or six degrees to the celestial east of) the waxing crescent Moon. With the Moon sliding east by its own diameter every hour, observers in more westerly time zones will see the Moon getting closer to the planet, allowing them to share the view in binoculars (green circle). Hours later, around 12:00 GMT, observers located in the southern half of Greenland and parts of far northern Canada can see the Moon occult Uranus, the last in a lengthy series of monthly occultations during 2022 and 2023. 

Saturday, February 25 – Lunar libration reveals elusive oceans (evening)

Lunar libration reveals elusive oceans on Feb. 25, 2023 at 7 p.m. (Chris Vaughan) | SkyNews
Lunar libration reveals elusive oceans on Feb. 25, 2023 at 7 p.m. (Chris Vaughan)

Due to the Moon’s orbital inclination and ellipticity, it tilts up-and-down and sways left-to-right up by to seven degrees while keeping the same hemisphere pointed towards Earth at all times. Over time, this lunar libration effect lets us see 59 per cent of the Moon’s total surface without leaving the Earth. 

You can observe libration yourself by noting the way major features move toward and away from the limb of the Moon, and up and down. Mare Crisium is a 345 mile (556 kilometre) diameter basin that is easy to see using your unaided eyes, and in binoculars, and telescopes. It is located near the eastern edge of the Moon, just north of the Moon’s equator (the up-down red curve). 

On Saturday, February 25, libration will shift Mare Crisium farther from the Moon’s edge. On the same evening, look closely for two dark patches positioned between Mare Crisium and the Moon’s edge. Those maria, named Mare Smythii and Mare Marginis, are difficult to see unless the Moon’s eastern limb is rotated towards Earth. 

Monday, February 27 – First quarter Moon (at 08:06 GMT)

First quarter Moon on Feb. 27, 2023 at 08:06 GMT. (Chris Vaughan) | SkyNews
First quarter Moon on Feb. 27, 2023 at 08:06 GMT. (Chris Vaughan)

When the Moon completes the first quarter of its orbit around Earth at 4:06 a.m. EST, 1:06 a.m. PST, or 08:06 GMT on Monday, February 27, 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 for viewing the lunar terrain when it is dramatically lit by low-angled sunlight. 

Monday, February 27 – Bright Moon passes Mars (overnight)

Bright Moon passes Mars on Feb. 27, 2023 at 11 p.m. (Chris Vaughan) | SkyNews
Bright Moon passes Mars on Feb. 27, 2023 at 11 p.m. (Chris Vaughan)

Mars will be the final planet that the Moon visits this month. After dusk on Monday evening, February 27, the waxing gibbous Moon will be shining brightly high in the southern sky. In easterly time zones Mars will be poised just two finger widths to the Moon’s left (or celestial east) — close enough to share the view in binoculars (green circle). As the hours pass, the Moon’s eastward orbital motion (green line) will carry it far closer to the red planet. Around 11 p.m. PST, (which converts to 1 a.m. EST and 05:00 GMT on Monday) the Moon will pass less than its own diameter to the north of Mars, allowing them to share the view in a telescope. Skywatchers located in Iceland north of Reykjavik and the Faroe Islands can see the Moon occult Mars around 05:00 GMT. 

Tuesday, February 28 – Venus prepares to pass Jupiter (early evening)

Venus prepares to pass Jupiter on Feb. 28, 2023 at 6:15 p.m. (Chris Vaughan) | SkyNews
Venus prepares to pass Jupiter on Feb. 28, 2023 at 6:15 p.m. (Chris Vaughan)

During late February, Venus will be swinging away from the Sun while Jupiter and the stars are carried sunward by Earth’s orbital motion. In the western sky during early evening on Tuesday, February 28, the two planets will shine in a close conjunction with brighter Venus positioned less than a thumb’s diameter below (or 1.3 degrees to the celestial west of) Jupiter, allowing them to share the view in a backyard telescope (green circle). The two planets will be binoculars-close from Saturday, February 25, to Monday, March 6. After their minimum separation on Wednesday, March 1, Venus will shine higher than Jupiter — to its celestial northeast. 

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.