Skywatch Line for Wednesday and Thursday, February 4 and 5, written by Alan French

This is Dudley Observatory’s Skywatch Line for Wednesday and Thursday, February 4 and 5, written by Alan French.

The Sun rose at 7:06 A.M. on Wednesday and sets at 5:12 P.M. On Thursday it rises at 7:05 A.M. and sets at 5:14 P.M. This Thursday gained 16 minutes, 48 seconds of daylight compared to last Thursday.

The Moon was full last Sunday and is now headed toward last quarter. On the waning gibbous Moon the terminator, the line between sunlight and darkness, is now the sunset line moving across the face of the Moon visible from Earth The terminator remains the sunset line until the next new Moon.

On Wednesday the Moon rises at 8:03 P.M. in the east and will be 88% sunlit when it rises. By 10 P.M. the Moon will be 14 degrees above the horizon. If you are up at 6 A.M. Thursday morning you will see an 86% illuminated Moon high toward the southwest. The Moon will set at 8:47 A.M. Thursday in the west.

On Thursday night the Moon will rise 9:43 P.M. toward the east and the rising Moon will be 80% sunlit. At 11:00 P.M. the Moon will be 12 degrees high toward the east southeast. At 6 A.M. Friday it will be 28 degrees above the southeastern horizon, and it will set at 9:06 A.M.

The Moon will reach last quarter next Monday morning.

Jupiter continues moving further into the evening sky, rising and transiting earlier. This Wednesday Jupiter rises at 2:35 P.M. and transits at 10:08 P.M. In three weeks, on February 25, it will rise at 1:04 P.M. and transit at 8:39 P.M. Planets are best viewed from Earth when they transit and are due south because that is when they are highest. It is, of course, also important that they transit at night when they are not washed out by the bright blue sky, and ideally, they should be well above the horizon when they transit. (Although a planet is highest when it is due south, it is not necessarily high in the sky.)

Jupiter is now 70 degrees above the southern horizon when it transits, so well up in the sky and our view of the gas giant is through a thinner layer of atmosphere and will tend to be steadier and detail easier to spot and photograph. Under good seeing there is a lot of detail to see in Jupiter’s atmosphere.

Jupiter’s atmosphere has high contrast cloud features that have been visible for centuries. The atmosphere has a light equatorial zone. To its north and south are the North and South Equatorial Belts. The north and south poles feature darker North and South Polar Regions. On a steady night with larger telescopes finer details can be seen within these features.

There is also the famous Great Red Spot (GRS), a large storm that has been visible for centuries protruding from the south side of the South Equatorial Belt. Sky Safari predicts the GRS will transit, be on Jupiter’s meridian, at 6:41 P.M. Wednesday.