Monday, March 20
Last Quarter Moon occurs at 11:58 a.m. EDT. You can find the half-lit orb rising in the east along with the background stars of Sagittarius around 2 a.m. local daylight time; it hangs relatively low in the south-southeast as twilight begins. Look about 3° to our satellite’s lower right and you should pick up the bright glow of Saturn. The ringed planet shines at magnitude 0.5, significantly brighter than any of Sagittarius’ stars. When viewed through a telescope, Saturn displays a 17"-diameter disk surrounded by a spectacular ring system that spans 38" and tilts 26° to our line of sight.
For those of you tired of winter weather, good news: Spring officially begins today. Earth’s vernal equinox occurs at 6:29 a.m. EDT, which marks the moment when the Sun crosses the celestial equator traveling north. The Sun rises due east and sets due west today. If the Sun were a point of light and Earth had no atmosphere, everyone would get 12 hours of sunlight and 12 hours of darkness. But our blanket of air and the finite size of our star make today a few minutes longer than 12 hours.
Tuesday, March 21
Mars continues to put on a nice show these March evenings. It appears nearly 20° high in the west once twilight fades to darkness and doesn’t set until after 10 p.m. local daylight time. The magnitude 1.4 Red Planet lies among the background stars of Aries the Ram. Unfortunately, Mars shows no detail on its 4"-diameter disk when viewed through a telescope.
Wednesday, March 22
One of the spring sky’s finest deep-sky objects, the Beehive star cluster (M44) in the constellation Cancer the Crab, lies high in the south around 9 p.m. local daylight time. With the naked eye under a dark sky, you should be able to spot this star group as a misty cloud of light. But the Beehive explodes into dozens of stars through binoculars or a small telescope.
Thursday, March 23
Mercury has started its finest evening appearance of the year for observers at mid-northern latitudes. The innermost planet lies nearly 10° above the western horizon a half-hour after sunset. Shining at magnitude –1.0, it stands out against the twilight glow through binoculars and should show up to the naked eye once you know where to look. A telescope reveals Mercury’s 6"-diameter disk, which appears three-quarters lit. The planet will reach the peak of this apparition at greatest elongation April 1.