This is Dudley Observatory’s Skywatch Line for Friday, October 23, through Sunday, October 25, written by Alan French.
The Moon reached last quarter this past Tuesday, so a waxing gibbous Moon will dominate the night sky this weekend. It will each full this coming Tuesday.
Early Friday night we can start our weekend with a view of the International Space Station (ISS) as it glides through the stars in the southwestern sky. It looks like a bright star moving across the sky.
The ISS will first appear at 6:54 pm moving up from the west northwestern horizon. It will be highest just after 6:57 pm when it will appear 45 degrees above the southwestern horizon. Finally, seconds after 7:00 pm, it will vanish below the southeastern horizon.
Its path will take it above bright, reddish Arcturus, below Corona Borealis, the Northern Crown, and then through Aquila, the Eagle, and below its bright luminary Altair. It will pass below the Moon as it approaches to horizon.
The dance of four planets in the morning sky continues, but Mercury is now rapidly moving lower each morning.
Look for the morning planets at 6:20 am on Saturday morning. Mercury will be just south of due east and a little over three degrees above the horizon, so you’ll need a good view down to the horizon and skies clear of haze and clouds. Brilliant Venus will be easy to spot, more than 30 degrees above the east southeastern horizon. Jupiter will be 1 ½ degrees to the lower left of Venus, and Mars will be about three degrees to the lower left of the pair.
By Sunday morning Mercury will have sunk to just under three degrees above the horizon at 6:20 am. Jupiter will be just over one degree to the left of Venus, and fainter reddish Mars will be to the lower left of the pair and 3 ½ degrees away.
By Monday morning Jupiter will be a above and to the left of Venus, still just over a degree away, with Mars remaining 3 ½ degrees below the duo. Mercury will be just two degrees above the horizon.
If the skies are not cooperating and Mercury is elusive because of its low altitude, you can try looking again later, perhaps at 6:45 am. On Saturday morning Mercury will be almost 8 degrees above the horizon by then. It will be a bit on Sunday and even lower on Monday morning – just over 6 degrees high.