A diagram of Ursa Major galaxies on April 9, 2021. | SkyNews
Ursa Major galaxies (Chris Vaughan, Starry Night Education)

This Week’s Sky: April 5 to 11, 2021

The crescent Moon will meet Saturn and Jupiter early this week. Later, as it wanes to new, it will be a fabulous time to check out some spring galaxies.

Tuesday, April 6 – Old Moon below Saturn (pre-dawn)

A diagram of Old Moon below Saturn, pre-dawn, April 6, 2021. | SkyNews
Old Moon below Saturn, pre-dawn (Chris Vaughan, Starry Night Education_

Look in the southeastern sky before dawn on Tuesday, April 6 for the waning crescent Moon positioned several finger widths to the lower right (or 4.5 degrees to the celestial south) of magnitude 0.75 Saturn. After the Moon rises at about 4:15 a.m. local time — about two hours before the Sun — you can view the Moon and the ringed planet together in binoculars. Since brighter Jupiter will be shining a short distance to their lower left, the grouping will make a nice photo opportunity when composed with some interesting landscape.

Wednesday, April 7 – Crescent Moon and Jupiter (pre-dawn)

A diagram of the Crescent Moon and Jupiter, pre-dawn, on April 7, 2021. | SkyNews
Crescent Moon and Jupiter, pre-dawn (Chris Vaughan, Starry Night Education)

The Moon’s visit with the bright morning planets will continue on the morning of Wednesday, April 7; however, the Moon won’t clear the southeastern horizon until after 5 a.m. local time. Once it does, it will sit less than a palm’s width below (or five degrees to the celestial south of) very bright, magnitude -2.1 Jupiter – close enough to view them together in binoculars. Include somewhat dimmer Saturn positioned to their upper right if you capture another nice photo.

Friday, April 9 – Ursa Major galaxies (all night)

A diagram of Ursa Major galaxies on April 9, 2021. | SkyNews
Ursa Major galaxies (Chris Vaughan, Starry Night Education)

The Big Dipper asterism and its home constellation of Ursa Major are very high in the northern sky in late evening during mid-April. It’s an ideal time to observe the spectacular galaxies they host in strong binoculars or backyard telescopes on the dark nights this weekend. Draw a line connecting the dipper stars Phecda to Dubhe, and extend it by an amount equal to their separation to arrive at the galaxy named Bode’s Nebula, otherwise known as Messier 81. It’s a magnitude 6.9 spiral galaxy oriented not quite face-on to Earth, making it appear relatively large and bright. A smaller, magnitude 8.4 galaxy named the Cigar Galaxy or Messier 82 is located half a degree to the north. That allows both galaxies to be viewed together in the eyepiece of a telescope at low magnification (inset). Several other fainter galaxies can be found within a few degrees of Bode’s Nebula.

A diagram of galaxies visible in Boötes. | SkyNews
Galaxies in Boötes (Chris Vaughan, Stellarium)

Chris Vaughan is all about those superb spring galaxies. Read more in the May/June 2021 edition of SkyNews and in the bonus online article, “Great April galactic adventures.”

Saturday, April 10 – Whirlpool and Pinwheel galaxies (all night)

A diagram of the Whirlpool and Pinwheel galaxies on April 10, 2021. | SkyNews
Whirlpool and Pinwheel galaxies (Chris Vaughan, Starry Night Education)

On evenings during April, the Big Dipper is positioned high in the northeastern sky. Under dark sky conditions two impressive galaxies can be seen in binoculars (red circle) and backyard telescopes by using the bright star Alkaid to locate them. That star marks the tip of the dipper’s handle. The Pinwheel Galaxy, or Messier 101, is a spectacular, large, face-on spiral galaxy positioned a palm’s width to the left (or 5.5 degrees to celestial north) of Alkaid, forming an equilateral triangle with Mizar, the double star at the bend of the handle. This relatively close galaxy (21 million light-years away) is nearly as large as the full Moon in the sky (inset). Since the galaxy’s light is spread over such a large area, its overall brightness is low. Aim your binoculars several finger’s widths to the upper right of Alkaid to discover the iconic Whirlpool Galaxy, aka Messier 51. This spiral galaxy’s angular size is smaller, but it will look somewhat brighter in your binoculars and telescope (inset). A secondary galaxy core designated NGC5195 alongside M51 is linked by a bridge of material.

Sunday, April 11 – New Moon (at 10:30 p.m. EDT)

A diagram of the New Moon on April 11, 2021. | SkyNews
New Moon (Chris Vaughan, Starry Night Education)

The Moon will officially reach its new phase on Sunday, April 11 at 10:30 p.m. EDT or 7:30 p.m. PDT. That translates to 02:30 Coordinated Universal Time (UTC) on Monday, April 12. 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 completely hidden from view from anywhere on Earth for about a day. After the new Moon phase Earth’s celestial night-light will return to shine in the western evening sky.

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.