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The Night Sky Tonight: April 20 – April 28

By Mark Wagner

Mark Wagner brings us highlights of what's happening in the sky each night this week. Click on each image to enlarge the view. Happy gazing!

Friday, April 20
Two great craters highlighted for you lunar fans tonight. Posidonius (A) is a 58 mile diameter circular crater on the Terminator tonight. Best in a 50mm instrument or larger, it has pretty high walls and lines of crests. The real treat is in 300mm instruments, so you can pick out the rimae crisscrossing the floor. Great crater! Theophilus (B) is deeply into the Terminator, but you may pick up one sunlit rim and the central mountain with four peaks. Under the right conditions, this is a tremendous view. 10X binoculars or larger.

Skill Level: Beginner

Suggested Gear: Orion Scenix 10x50 Wide-Angle Binoculars, Orion SkyQuest XT12i IntelliScope Dobsonian Telescope

Tomorrow Morning: Veil Nebula in Cygnus

Saturday, April 21
The Veil Nebula will benefit from darker skies, with enhancement from an Orion Ultrablock narrow band filter. Here is a sketch of the Veil passing through 52 Cygni, an easy target along the constellation's leading wing. A remnant from a supernova, thought to have occurred thousands of years ago, 2500 light years away. The entire Veil Nebula is 1.2 degrees wide, more than twice the diameter of a Full Moon. In a dark sky the Veil is one of the most beautiful of all celestial sights!

Skill Level: Intermediate

Suggested Gear: Orion SkyQuest XT8 PLUS Dobsonian Reflector Telescope, 2" Orion UltraBlock Narrowband Eyepiece Filter

Tomorrow Evening: Lyrid Meteor Shower

Sunday, April 22
Once the First Quarter Moon sets, the Lyrid meteor shower will improve in visibility, so better to wait until close to 3 A.M. tomorrow morning. "The Lyrids are a medium strength shower that usually produces good rates for three nights centered on the maximum. These meteors also usually lack persistent trains but can produce fireballs. These meteors are best seen from the northern hemisphere where the radiant is high in the sky at dawn. Activity from this shower can be seen from the southern hemisphere, but at a lower rate."

Skill Level: Beginner

Suggested Gear: Orion FunScope Astro Dazzle 4.5" TableTop Telescope Kit, Orion UltraView 10x50 Wide-Angle Binoculars

Tomorrow Morning: Open Cluster NGC 6940

Monday, April 23
With Cygnus up high in the morning skies, try for the nice open cluster NGC 6940, just west of the Veil Nebula and 52 Cygni. The cluster is 25 arc-minutes in diameter, nearly the size of our Full Moon. At magnitude 6.3 it is a good binocular target, just over Cygnus' border into Vulpecula. It is 2500 light years from us and around 1 billion years old. Sir William Herschel discovered it in 1784.

Skill Level: Beginner

Suggested Gear: Orion StarBlast II 4.5 Equatorial Reflector Telescope, Orion GiantView 15x70 Astronomy Binoculars

Tomorrow Evening: Mooning!

Tuesday, April 24
Tonight the Moon is sits 4 degrees east of Regulus in Leo in waxing gibbous phase. Here are three fine targets. The craters Copernicus (B) and Stadius are good in 30 mm and 50 mm instruments. Stadius has very high walls and slopes, reaching up to 10,800 feet, a flat floor and interesting central peak. Copernicus is right on the Terminator so will have dramatic lighting. Note the rays and three central peak on a large flat floor enclosed by steep slopes. Clavius (C) is fine in binoculars, famous for its curved chain of interior craters. It is the largest of these targets, at 136 miles diameter.

Skill Level: Beginner

Suggested Gear: Orion Observer II 70mm Equatorial Refractor Telescope, Orion Otter ED 10x42 Waterproof Binoculars

Tomorrow Morning: Colorful Double Star Alberio

Wednesday, April 25
Shining yellow/gold and sapphire blue, the binary star Alberio (Beta Cygni) is always a favorite. It is easy to locate, west of Cygnus' alpha (A) star Deneb. At a distance of 386 light years, it is 60 solar radii and has a luminosity of 1345 Suns! The primary is magnitude 3.1 and the blue dwarf secondary magnitude 5.1, separated by 35 arc-seconds, wide enough to try in binoculars. The combined magnitude of the pair is 3.03. If you've never viewed this and do not yet own a telescope, go to a local astronomy club star party and see it!

Skill Level: Beginner

Suggested Gear: Orion SkyQuest XT6 PLUS Dobsonian Reflector Telescope, Orion GiantView ED 16x80 Waterproof Astronomy Binoculars

Tomorrow Evening: Seeing the Ecliptic

Thursday, April 26
The Ecliptic is the path along which most solar system objects appear to move. It effectively described the equator of our solar system, which it steeply tilted to that of our galaxy. Here you can see two Zodiacal constellations, Leo and Virgo, and our Moon between them, all near the Ecliptic. The Moon moves along dipping south and then again north of the Ecliptic, in a narrow path. As such, the Moon occasionally occults the bright stars along the Ecliptic, such as Spica and Regulus. You can see dates along this depiction of the Ecliptic, showing when the Sun is in various locations along our orbit.

Skill Level: Beginner

Suggested Gear: Orion StarBlast 6 Astro Reflector Telescope, Orion SkyQuest XT8 Classic Dobsonian Telescope

Tomorrow Morning: Io Shadow Transit and Great Red Spot

Friday, April 27
It?s use-it-or-lose-it time with morning Jupiter. The planet is in retrograde and heading for the horizon by mid-May, but rising in the evening for night-time observers. Today its moon Io is approaching the disk of Jupiter an hour before sunrise, preceded briefly by Io's shadow. You can also get a view of the Great Red Spot (GRS) as it readies to rotate out of view. Losing our morning target may be sad news, but it will soon be easier and easier to view it at night!

Skill Level: Beginner

Suggested Gear: Orion StarMax 90mm TableTop Maksutov-Cassegrain Telescope, Orion StarSeeker IV 114mm GoTo Reflector Telescope Kit

Tomorrow Evening: Big Moon Targets

Saturday, April 28
The Moon can't get much bigger with Full Moon occurring tomorrow. Let's explore the lunar limb. Start with Hevelius (A) near the equator. A good target in binoculars, this 64 mile diameter crater has low walls, a flat floor, and rimae good at high power. Its neighbor to the south is Grimaldi (B), looking much like a lunar sea. This is a dark area of very flat and "somber" lava containing many craterlets. Far to the south is Wargentin, a circular pyroclastic area of lava filled to the top of the crater, just below the large crater Schickard, seen above and to the left. Have fun with these!

Skill Level: Beginner

Suggested Gear: Orion ShoreView Pro 10x42 Waterproof Roof Prism Binoculars, Orion Observer 80ST 80mm Equatorial Refractor Telescope Kit

Tomorrow Morning: Full Moon and Io Shadow Transit

Charts from Starry Night Pro, available from Orion Telescopes & Binoculars. Lunar photos courtesy Robert Reeves. Veil Nebula and Alberio sketches by Jeremy Perez. NGC 6940 image from Moon globe images from Virtual Moon Atlas. Other images from Starry Night Pro. Lyrid quotation is from the American Meteor Society.

Mark Wagner is a lifelong astronomy enthusiast and deep sky observer in the San Francisco bay area. Visit our Facebook Page if you'd like to post comments, questions, sketches or images you've taken to our Night Sky Tonight post.