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The Night Sky Tonight: March 17 – March 25

By Mark Wagner

Friday, March 17
Big night on Jupiter! Midnight brings the Great Red Spot (GRS) and shadow of the moon Ganymede transiting the planet. By 2 a.m. the shadow transit is leaving the disk as the GRS crosses the meridian. At 3:38 a.m. Ganymede and the GRS will begin rotating out of view, just as the moon Io comes out from behind the planet, appearing first as a small bump before separating, followed quickly by Ganymede emerging off the face of planet. There is always action to observe on Jupiter, whether it is the GRS, its moons, shadow transits, or activity in the clouds of the belts. Get out your telescopes, Jupiter season is here!

Skill Level: Beginner

Suggested Gear: Orion AstroView 90mm Equatorial Refractor Telescope, Orion SpaceProbe 130 EQ Reflector Telescope

Tomorrow Evening: Deep Sky In Canis Major

Saturday, March 18
M41 was discovered by Giovanni Batista Hodierna prior to 1654, and may have been viewed by Aristotle around 325 B.C. At magnitude 6.3 it is nearly naked-eye visible in dark skies. The cluster's diameter is around 25 light years and is receding from us at 23.3 km/s. At 190M years of age, the stars are expected to disperse in another 310M years. Noted observer Walter Scott Houston wrote, "Many visual observers speak of seeing curved lines of stars in M41. Although they seem inconspicuous on photographs, the curves stand out strongly in my 10" telescope, and the bright red star near the center of the cluster is prominent." You can view M41 in binoculars. If you have an observation of this - share it with us on our Facebook page!

Skill Level: Beginner

Suggested Gear: Orion 15x70 Astronomy Binoculars with Tripod Adapter, Orion SkyQuest XT10 Classic Dobsonian Telescope

Tomorrow Morning: The Term Conjunction

Sunday, March 19
The term "conjunction" in astronomy refers to two or more celestial bodies in close alignment. Conjunctions usually involve the Sun or Moon and other objects. Conjunctions occur frequently and can also involve planets in close proximity, or planets being near bright stars or deep sky objects. Tomorrow morning early risers will see a conjunction of Saturn, the Moon "and" the vernal equinox! This image shows what you should see looking south.

Skill Level: Beginner

Suggested Gear: Orion Star Target Planisphere, 30-50 degree, Orion DeepMap 600 Folding Star Chart

Tomorrow: Vernal Equinox

Monday, March 20
Today is the vernal equinox (2), the beginning of spring in the northern hemisphere, and fall south of the equator. At the equinox, the Sun's rays fall directly perpendicular to the equator, where day and night will be equal in length. Other notable seasonal events include summer and winter solstices, autumnal equinox, and four cross-quarter days that mark the midpoints between the equinoxes and solstices. Cross-quarter days are celebrated holidays, including Groundhog Day on Feb. 2, May Day on May 1, Lammas on Aug. 1, and All Souls? Day, or Halloween, on Oct. 31.

Skill Level: Beginner

Suggested Gear: Orion Star Target Planisphere, 30-50 degree, Orion DeepMap 600 Folding Star Chart

Tomorrow Morning: Lunar Observing

Tuesday, March 21
This morning's waning crescent Moon offers excellent telescope and binocular views, with the terminator slicing through Mare Imbrium, Mare Insularum and Mare Nubium. Suggested targets are the combination of Craters Eratosthenes (A) and Copernicus (B), and Tycho (C). All will show nicely in 10X binoculars, and yield tremendous high contrast detail at higher power in telescopes. Enjoy the nice chain of craterlets running north/south between Eratosthenes and Copernicus. Lunar imagers, please post your shots images of these areas here.

Skill Level: Beginner

Suggested Gear: Orion MoonMap 260, Orion AstroView 90mm Equatorial Refractor Telescope

Tomorrow Evening: Open Cluster Treat in Canis Major

Wednesday, March 22
Have you ever seen a jumping star? Tau Canis Majoris is centered on NGC 2362, a bright, magnitude 4.0 open cluster 8 arc-minutes in size, containing about 40 stars at a distance of 4,000 light years. The cluster is among the youngest known, at a 5 million years. View it at higher power and tap your telescope. Tau, the brightest star, will appear to jump around relative to the dimmer stars of the cluster. The effect is very striking! Try it and let us know if you see it happen.

Skill Level: Intermediate

Suggested Gear: Orion SkyQuest XT8 Classic Dobsonian Telescope, Orion DeepMap 600 Folding Star Chart

Tomorrow Morning: More Jupiter fun!

Thursday, March 23
Start your day with this excellent view of Jupiter, showing off its Great Red Spot (GRS), its moon Io's shadow in transit, and Io approaching ingress on the planet?s disk. Keep an eye on Io, as it will skirt the northern edge of the Northern equatorial belt. See if you can follow it. You may also be amazed at the speed at which both the preceding shadow and the moon transit the planet, relative to the GRS. We'll soon be watching Jupiter in the evening, as it will reach opposition soon. It currently rises around 8:30 p.m.

Skill Level: Beginner

Suggested Gear: Orion SpaceProbe 130 EQ Reflector Telescope, Orion StarSeeker IV 127mm GoTo Mak-Cass Telescope

Tomorrow Evening: Interesting Double Star in Canis Major

Friday, March 24
Epsilon Canis Majoris, common name Adhara, can be a challenging double star due to the wide difference in magnitudes. The primary is magnitude 1.5 and its companion 7.5, with a separation of 7". Reports of splitting it exist in instruments as small as 92mm, but 5"-6" or larger is more common. The star itself is amazing. At a distance of 432 light years, it was the brightest star in the sky 4.7 million years ago, at magnitude -3.99, roughly equal to Venus (see Venus tonight in the West at sunset). How bright do you think our Sun would appear if moved to the distance of Adhara?

Skill Level: Beginner

Suggested Gear: Orion AstroView 6 Equatorial Reflector Telescope, Orion StarSeeker IV 150mm GoTo Reflector Telescope

Tomorrow Morning: An Unusual Globular Cluster In Sagitta

Saturday, March 25
M71 is an easy to locate globular cluster in the constellation Sagitta. At magnitude 8.19 and angular size of 7.2 arc-minutes, it is visible in 50mm binoculars in magnitude 5 skies. "Despite being a familiar object, Messier 71's precise nature was disputed until recently. Was it simply an open cluster, a loosely bound group of stars? This was for many years the dominant view. But in the 1970s, astronomers came to the view that it is in fact a relatively sparse globular cluster." Use Alberio (B) and Altair to find Sagitta, and hop to this curious cluster.

Skill Level: Beginner

Suggested Gear: Orion UltraView 10x50 Wide-Angle Binoculars, Orion SpaceProbe 130ST Equatorial Reflector Telescope

Tomorrow Morning: Checking Out Saturn

Charts from Starry Night Pro, available from Orion Telescopes & Binoculars. M41 sketch courtesy Jeremy Perez Belt Of Venus Blog. NGC 2362 image courtesy Wikisky.org. Vernal Equinox image courtesy NASA. M71 image and quotation from ESA/Hubble and NASA. Data from Starry Night Pro 6 and Wikipedia.

Mark Wagner is a life-long 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.