Skywatch Line for Monday and Tuesday, March 10 and 11, 2025, written by Alan French
This is Dudley Observatory’s Skywatch Line for Monday and Tuesday, March 10 and 11, 2025, written by Alan French.
Early Monday morning, we set our clocks ahead one hour, changing to Daylight Saving Time. The Sun rises at 7:15 A.M. on Monday and sets at 6:56 P.M. On Tuesday it rises at 7:14 A.M. and sets at 6:57 P.M. We will get our hour back, if nothing changes, returning to Standard Time, on the first Sunday in November.
With Mercury fading and moving lower into evening twilight we are running out of time to spot elusive Mercury soon after sunset. You will need a good view west with clear skies. It is best to start looking around 30 minutes after sunset. Much earlier and the sky will be too bright, much later and Mercury will be too low.
Begin looking for Mercury at 7:30 P.M. Brilliant Venus, at magnitude -4.4, low in the west, is an excellent guidepost. On Monday Venus will be 13 degrees above the horizon at 7:30. Mercury will be just under 6 degrees away, to the lower-left at about the 8 o’clock position, and 10 ½ degrees above the horizon. Mercury is magnitude +0.2, more than a magnitude fainter than at its brightest, and you may need binoculars to spot it against evening twilight. By 7:45 P.M. the sky will be darker, which will help spotting it by eye. Mercury will then be 8 degrees above the horizon. (For reference, the first three fingers held together and at arm’s length, span 5 degrees across their tips.)
On Tuesday Venus will be 12 degrees high at 7:30 P.M. and Mercury will be 5 ½ degrees away, more to the left than below, approaching the 8:30 o’clock position. It will be 10 ½ degrees high and magnitude +0.4. By 7:45 Mercury will just under 8 degrees high. Over the next week Mercury will fade more than two magnitudes and next Tuesday the planet will be only 5 ½ degrees high 30 minutes after sunset. Venus will have moved even lower, lying just 4 degrees above the horizon, but still at magnitude -4.1.
The Moon reached first quarter this past Thursday and is now moving toward full and a waxing gibbous Moon will grace the night sky.
On Monday night at 8:00 P.M. look for a 90% sunlit Moon 48 degrees above the east southeastern horizon. The Moon will be due south at 10:53 P.M. and will not set until 6:18 A.M. Tuesday.
By Tuesday at 8:00 P.M. a 95% illuminated Moon will lie 37 degrees above the east southeastern horizon. The Moon will be in Leo, the Lion, with the constellation’s brightest star, Regulus, 4 degrees blow the Moon. It in the south at 11:39 P.M. and will not set until 6:41 A.M. Wednesday. The Moon will be full early this coming Friday.