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Astro Bob: Jupiter-moon mash-up / BlueWalker 3 stalks the sky

We anticipate the moon's next move and learn about a new satellite constellation that may significantly alter our experience of the night sky.

Full moon and Jupiter
Jupiter, the "star" at left, rises alongside the Harvest Moon over Lake Superior in Duluth on Saturday night, Sept. 10.
Contributed / Bob King
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DULUTH — Clouds blocked Saturday's moonrise here, so I didn't get to see Jupiter and the Harvest Moon crest the horizon together. I hope you were luckier. Fortunately, 15 minutes later, they both shared a narrow slot of clear sky and made for an alluring sight. We may curse clouds when they hide our favorite cosmic baubles, but they add so much to a moonlit scene.

Moon and Jupiter
In a day's time, the moon travels about 13° to the east. On Sunday night (Sept. 11), it follows below and behind Jupiter.
Contributed / Stellarium

On Sunday night, Sept. 11, the moon will rise about 20 minutes later and shine below and left of the mighty planet, offering a dramatic demonstration of just how far it travels eastward in 24 hours. I hope you'll be watching. The moon's next planetary play date is scheduled for Sept. 16-17, when it sidles up alongside Mars. I love these routine yet special visits. They add zest and anticipation to a night of stargazing.

BlueWalker 3 satellite launch

On Sept. 10, SpaceX launched another batch of 34 Starlink satellites into orbit along with a brand new craft built by AST SpaceMobile , the BlueWalker 3. Billed as the largest commercial satellite ever made, this 1.5-ton behemoth, shaped like a giant computer chip, has a surface area of 693 square feet (64 square meters). It rode into space folded into a much smaller package; in the coming days, it will unfold to the size of a squash court.

BlueWalker 3
This is the BlueWalker 3, a prototype satellite that will unfold into a large antenna array. The back side of the array is lined with solar cells to power the system.
Contributed / AST SpaceMobile

BlueWalker 3 is a prototype satellite with numerous sub-antenna modules that will connect directly to ordinary smartphones to provide broadband 4G coverage virtually anywhere on Earth. Think of it as an orbiting raft of cell phone towers.

Before it becomes fully operational, engineers will conduct tests to demonstrate that the technology works in low Earth orbit in coordination with infrastructure on the ground. Testing locations include the company's home state of Texas, along with Hawaii and AST's cellular partners in Europe, Japan, South America, Africa and Asia.


Now for the potentially bad news, at least as far as astronomy and skywatching are concerned. Assuming all goes to plan, the company will work with SpaceX and possibly other providers to launch about 110 significantly larger satellites called BlueBirds into orbit to establish a full network by the year 2024.

While that number pales in comparison to the current (and planned) number of Starlinks, BlueBirds will be considerably larger and therefore likely MUCH brighter, making a significant addition to the number of bright satellites tracking through the night sky. Some observers expect them to become the second brightest objects after the International Space Station.

BlueWalker 3 in orbit
In this artist's view, we see BlueWalker 3 in orbit. The array will circle the Earth about every 90 minutes.
Contributed / Nokia, AST SpaceMobile

Everyone, from amateurs like you and I to professional astronomers, are concerned about the impact. Will their light compromise our view of faint cosmic objects? What about the aesthetic experience of a night sky with a minimum of human interference? That's not all. There are 30,000 new, next-generation Starlink satellites waiting for FCC approval that may also carry antennas for cell phone connectivity. While these birds are only 269 square feet (25 square meters) across, there are a whole lot more of them!

Tony Mallama , who worked on the Hubble Space Telescope, is interested in how bright BlueWalker 3 and the BlueBirds will shine and asks for your help in monitoring their brightness. Once BlueWalker 3 deploys, I will post when and where you can see it along with a list of stars you can use to compare and estimate its brightness. You send me your brightness estimates, and I'll forward them to Mallama. Deal? Good.

Stay tuned for an update!

"Astro" Bob King is a freelance writer and retired photographer for the Duluth News Tribune. You can reach him at nightsky55@gmail.com.
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