Skywatch Line for Monday, February 22, and Tuesday, February 23, 2021

This is Dudley Observatory’s Skywatch Line for Monday, February 22, and Tuesday, February 23, written by Alan French.

The technological success of Perseverance was exciting and it was a thrill to hear it was safely on Mars. While we couldn’t watch it directly, someone was carefully positioned and ready to take a quick look – the HiRISE (High Resolution Imaging Science Experiment) camera on the Mars Reconnaissance Orbiter. Through meticulous planning the HiRISE camera caught an image of Perseverance below its huge parachute as it descended toward Mars. You can see the image at HiRISE | The Descent of Perseverance (Mars 2020) (ESP_068281_9024 (

Reaching first quarter last Friday, a waxing gibbous now dominates the evening sky. As the Sun sets look for a lovely Moon in the eastern sky. The Moon will be 79% illuminated on Monday night and 87% full on Tuesday. It will travel high across the sky both nights and will be up much of the night. It reaches full early next Saturday morning.

If you are up bright and early on Tuesday morning there is a lovely pass of the International Space Station (ISS) visible from our area just before 5 A.M.. We see satellites because they are up in sunlight while we are still down in the Earth’s shadow. Because the ISS is large it reflects a lot of sunlight and is the brightest satellite gliding through our skies. When high above the horizon it outshines the brightest stars and rivals the brightest planets.

Sometimes we can’t see the ISS pass entirely across the sky, because it either moves into or out of the Earth’s shadow while above the horizon. Tuesday morning’s pass has the ISS emerge from the shadow when 61-degeees above the south-southwestern horizon.

Just before 5 A.M. look high toward the south southwest for the bright, reddish star Arcturus. If you have the right star you’ll see a kite-shaped pattern of stars above it. The ISS, moving out of the Earth’s shadow and into view, will pass just to the left of Arcturus at 4:59:50. It will then move toward the northeast, passing close to bright Vega just before 5:01 A.M., and then pass through, Cygnus, the Swan, as it moves toward the horizon and fades from view. (Some of you may know Cygnus as the Northern Cross.)

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