Crescent Moon over the Hyades Cluster
Crescent Moon over the Hyades Cluster
This Week’s Sky: March 23 to 29

Tuesday is a big day this week — look for evening Zodiacal light, Venus at its greatest eastern elongation and Mercury at its greatest western elongation.

Tuesday is a big day this week. With a New Moon allowing dark skies to see everything, look for evening zodiacal light, Venus at its greatest eastern elongation and Mercury at its greatest western elongation. If you happen to be in southeast Asia or Australia, you can also scope out a double shadow transit on Jupiter.

Tuesday, March 10 to Tuesday, March 24, after evening twilight – Evening zodiacal light

Evening zodiacal light

For about an hour after dusk during the two-week period preceding the new moon on March 24, Northern Hemisphere observers can look west-southwest for a broad wedge of faint light rising from the horizon. It will be below Venus and centred on the ecliptic (green line). This is the zodiacal light — reflected sunlight from interplanetary particles of matter concentrated in the plane of the solar system. You will need to observe from a location without light pollution. Don’t confuse the zodiacal light with the brighter Milky Way to the northwest.

Tuesday, March 24 pre-dawn – Mercury at greatest western elongation

Mercury at greatest western elongation

On Tuesday, March 24, the planet Mercury will reach its greatest angle of 28 degrees from the Sun, and peak visibility, for this morning apparition. Look for swiftly-moving planet sitting very low in the eastern sky between about 6:30 and 7 a.m. in your local time zone. The shallow angle that the morning ecliptic (green line) makes with the eastern horizon will make this apparition a poor one for Northern Hemisphere observers — sorry, Canadians — but an excellent showing for those located near the Equator, and farther south.

Tuesday, March 24 at 9:28 GMT – New Moon

New Moon

At its new phase, the Moon is travelling between the Earth and the Sun. Since sunlight is only reaching the side of the Moon aimed away from us, and the moon is in the same region of the sky as the Sun, the Moon is hidden from view for about a day.

Tuesday, March 24 from 19:37 to 21:53 GMT – Double shadow transit on Jupiter

Double shadow transit on Jupiter

Again, sorry, Canada — this one’s not for you. But we thought we’d leave it on the list for any international readers.

From time to time, the small round black shadows cast by Jupiter’s four Galilean moons become visible in amateur telescopes as they cross (or transit) the planet’s disk. On Tuesday, March 24, observers located across China, Southeast Asia, and Australia can see two of those shadows on Jupiter at the same time. At 19:37 GMT, Io’s shadow will join Ganymede’s larger shadow already in transit. The shadows will cross Jupiter together for 136 minutes until both of them move off the planet at 21:53 GMT.

Tuesday, March 24 evening – Venus at greatest eastern elongation

Venus at greatest eastern elongation

On Tuesday, March 24, Venus will officially reach its widest separation of 46 degrees east of the Sun. Viewed in a telescope, the planet will exhibit a half-illuminated phase. For best results, view the planet during evening twilight when contrast between the bright planet and the surrounding sky is reduced. After today, our sister planet will continue to brighten and increase in apparent disk diameter as it swings back toward the Sun and inferior conjunction in early June.

Thursday, March 26 after dusk – Young Moon and Uranus

Young Moon and Uranus

In the western sky after dusk on Thursday, March 26, the very young, Crescent Moon will be positioned a palm’s width to the lower left (or seven degrees to the celestial south) of Uranus. Encounters of the Moon and Uranus normally leave the relatively faint magnitude 5.8 planet overwhelmed by the bright moonlight — but this six-per-cent illuminated Moon will be far less bothersome. Here at the end of its viewing season, Uranus will be quite low in the sky. Try to observe it using binoculars or your backyard telescope as soon as the sky has darkened. That way you’ll be viewing it through the least amount of distorting air.

Saturday, March 28 evening – Crescent Moon meets Venus, Vesta, and the Seven Sisters

Crescent Moon meets Venus, Vesta, and the Seven Sisters

In the western sky after dusk on Saturday, March 28, the waxing Crescent Moon will make a pretty sight as it forms a triangle to the left of Venus and the bright little open star cluster known as the Pleiades, or the Seven Sisters. The Moon, planet and star cluster will span an area of sky smaller than an outstretched fist’s diameter, making a pretty widefield photograph. The main belt asteroid Vesta will be positioned less than four finger widths above the Moon.

Sunday, March 29 evening – Crescent Moon over the Hyades Cluster

Crescent Moon over the Hyades Cluster

During the evening on Sunday, March 29, in the western sky, the waxing Crescent Moon will be positioned above (or to the celestial northeast of) the large open star cluster known as the Hyades that outlines the triangular face of Taurus, the Bull. The Moon will also sit to the upper right of bright, orange-tinted Aldebaran. That star, which marks the bull’s left-hand or southerly eye, is less than half as far away as the cluster’s stars. The Moon, Aldebaran, and the Hyades will all fit nicely within the field of view of binoculars (red circle).

Monday, March 30 pre-dawn – Mars meets Messier 75

Mars meets Messier 75

In the southeastern pre-dawn sky on Monday, March 30, Mars’ orbital motion (red path with dates and times) will carry it 0.75 degrees to the north of a globular star cluster designated Messier 75. The fuzzy grey cluster, located more than 67,000 light-years away from us, and the Red Planet, located a mere 12 light-minutes away from Earth, will fit together in the field of view of a backyard telescope at high magnification (red circle). (Your optics will likely flip and/or invert the view shown here.) Look for Saturn sitting nearby — on the opposite side of Mars from the cluster. 

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.

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