Skywatch Line for Wednesday and Thursday, February 28 and 29, 2024, written by Alan French

This is Dudley Observatory’s Skywatch Line for Wednesday and Thursday, February 28 and 29, 2024, written by Alan French.

The Sun rises at 6:33 A.M. on Wednesday and sets at 5:43 P.M. On Thursday it rises at 6:32 and sets at 5:44. This Thursday has just under 19 minutes more daylight than last Thursday. We will have gained 1 hour, 15 minutes of daylight in February when the month is over.

The Moon was full last Friday and is moving toward last quarter. On Wednesday night an 82% illuminated, waning gibbous Moon rises at 10:00 P.M. toward the east. Thursday morning look for the Moon toward the southwest as dawn first appears. The Moon will set at 8:32 A.M. On Thursday night the Moon will rise in the east southeast at 11:06 P.M. and it will be 73% sunlit. Moonset on Friday is at 8:55 A.M. The Moon
will reach last quarter on Sunday.

You may have heard the recent full Moon called a micro-Moon. Our Moon’s orbit is elliptical, so its distance from us varies, which means its apparent size also changes. At its closest, the Moon averages about 362,600 km (237,736 mi.) away, and at its farthest it averages 405,400 km (251,904 mi.) from us.

We use angular measurements for distances across the sky and for the size of celestial objects. If we had a perfect, unobstructed horizon, it would be 180 degrees from one side to the other. The Moon spans ½
degree. Each degree is divided into 60 arcminutes (‘), so the Moon spans 30 arcminutes. For small objects, each arcminute is divided into 60 arcseconds (“). Jupiter, now toward the west southwest early in the
evening, spans 33.5 arcseconds, too small to see as a disc by eye, although its brightness may make it appear larger than stars.

Because of its varying distance, the Moon’s apparent size varies. At is closest it appears 33 arcminutes across, at its farthest 29 ½ arcminutes, a difference of about 11% in apparent size.

Before 1979 people paid little attention to this modest variation in the apparent size of the Moon. According to the Internet, an astrologer first called the coincidence between a full Moon and an unusually close Moon a “Super Moon.” It gradually caught on with the media, and now we often hear about these Super Moons. We also hear about micro-Moons, when the full Moon occurs when the Moon is near its farthest distance from Earth. The February 24 full Moon was the farthest and smallest of 2024.

At least one online site has declared the full Moons of August, September, October, and November, as “Super Moons.” According to the Royal Astronomical Society of Canada’s “Observer’s Handbook 2024,” the largest full Moon of 2024 is on October 17. The numbers show the full Moon early on September 18, late on the evening of September 17 for us, a close second.