Many of you have seen the International Space Station (ISS). Biggest and brightest of the satellites, it's hard to miss. Right now, it crosses the morning sky at dawn and won't return for evening observation until mid-November. While it's true the sky's a little emptier without the space station, there are other satellites worth seeing, even if they're not as shiny. Let's meet two: the Chinese space station Tiangong and the Air Force's X-37B.
Between 2011 and 2019, the Chinese sent up two prototype stations, Tiangong-1 and Tiangong-2, with the goal of perfecting the technology needed to build a long-term space station. After fulfilling those mission goals, both spacecraft were de-orbited and burned up in the atmosphere in 2018 and 2019, respectively. The current Tiangong (or "heavenly palace") is the real ticket.
The station's first or core module lifted off last April. Two months later, the first astronauts, called taikonauts (Mandarin for "space"), docked and made it their home until September. Two more modules will follow. When completed in 2022, Tiangong will be about a third the size of the ISS with a crew capacity up to six people. The ISS can house nine.
Like the U.S. space station, Tiangong will be an orbiting laboratory with more than 1,000 experiments currently under consideration. Since the 1998 launch of the ISS, astronauts have conducted more than 3,000 experiments within its aluminum walls.
The latest Chinese crew blasted off for Tiangong on Oct. 15 and included 41-year-old Wang Yaping, the first female taikonaut to crew the station. They'll stay for six months before returning home.
With a new crew in place and Tiangong making convenient evening passes through the end of October, why not have a look yourself? Just remember that the Chinese station won't shine as brightly as the ISS because it's quite a bit smaller. From the central and southern U.S. it can reach first magnitude (like Deneb in the Northern Cross). But in the northern U.S. it tracks lower in the sky, and only achieves second magnitude, the same brightness as the Big Dipper stars.
To find it, go to Heavens Above. If your city doesn't show up in box at the upper right click the blue Change Your Observing Location link under the Configuration heading on the left side of the page. Once your location is set, click the blue Tiangong link for a list of passes. In the Brightness (mag.) column, pick the passes of magnitude 2.5 or brighter. The smaller the magnitude value the brighter the object.
Times are given on the 24-hour clock, sometimes called military time. Noon is 12:00; 6 p.m. is 18:00 and 00:00 is midnight. Tiangong will be brightest, highest and easiest to see at the times listed in the Highest Point column. Click on that time and a map will pop up showing the station's arc across the sky. If the arc extends a short distance and then ends, it means that the satellite will enter Earth's shadow and no longer be visible.
Be sure to go outside about 10 minutes before Tiangong comes by to allow your eyes time to dark-adapt. It will also give you a chance to get oriented, so you'll know what direction to look when the satellite sails highest in the sky.
You'll also have a chance through about October 27 to spot another satellite, X-37B. If that name sounds all secret and experimental you are correct! The X-37B is an unmanned, orbital test vehicle for the U.S. Air Force — like a miniature space shuttle without a pilot. A rocket boosts it into orbit, and the craft returns on its own as a space plane.
The Air Force's primary objectives are to test reusable spacecraft technologies and run experiments in space that can be returned to Earth. While the missions are secret, anyone can see the craft when it's orbiting. I caught sight of it a couple of nights ago in a bright, moonlit sky when it briefly brightened to first magnitude while crossing the constellation Aquila the Eagle.
The X-37B really does look like a kiddie-car space shuttle. It's only about 29 feet (8.8 meters) long and 9.5 feet (2.9 meters) tall, with a wingspan of about 15 feet (4.6 meters). Because its missions are classified there's been chatter that maybe it's some kind of space weapon. But the amount of cargo space and lack of maneuverability make this unlikely.
While you and I may never know the content of its missions at least we can see it fly by in orbit Just follow the same instructions you did for Tiangong but click the blue X-37B link instead. Unlike the ISS, which is bright throughout its track, the X-37B only reaches its peak brightness for a short time when highest in the sky. Be sure you're looking in that direction at that time. And like Tiangong, choose passes where it's magnitude 2.5 or brighter.
Now all you need is a clear sky, which I hope happens tonight!
"Astro" Bob King is a freelance writer for the Duluth News Tribune. Read more of his work at duluthnewstribune.com/astrobob.