Late on April 13th a few of us watched minor display of the aurora borealis pop up low in the northern sky before midnight. Hours earlier, astronauts on board the International Space Station (ISS) caught sight of their southern counterpart called the aurora australis as their ship sped over the Southern Ocean at more than 17,000 miles an hour. One member of the crew took a photo of the display, which danced below their ship. Auroras typically appear between 70 and 125 miles (112-200 km) high; the ISS at the time was 266 miles (428 km) up so the crew looked down to view the lights.
But the photo records more than aurora. It also includes a string of 16 Starlink satellites orbiting at approximately 250-310 miles (400 to 500 km) altitude — equal to or a little higher than the space station. There are currently 360 in orbit with a total of at least 12,000 planned. Linked together into several “constellations” at different altitudes the satellites will eventually provide Internet access around the globe.
Starlinks are packed like stacked chairs into nosecone-looking compartment called a fairing and launched atop a SpaceX Falcon-9 rocket. The next launch, which will also include an Argentine radar satellite, had been planned for March 30 but travel restrictions due to the coronavirus prevented the Argentine personnel from flying to Florida for the launch. SpaceX, the company headed by Elon Musk that built the satellites, also had some COVID-19 problems of its own. Two workers there tested positive, prompting Musk to send some of the staff home to quarantine for 14 days.
The new launch date is April 23 at 3:16 p.m. EDT (moved up to April 22 at 4:37 EDT). If you’re lucky you can see them as soon as that evening when they’re bunched together like a popcorn on a string. If that happens over the U.S. and Canada this time around I’ll alert you and provide directions on when and where to see them. In the meantime you can go out almost any night and see at least a few Starlinks playing follow the leader. I watched them rise out Gemini and pass under the Big Dipper a few nights ago.
To find out if they’re out tonight for your town, go to Heavens Above, set your location (box at the upper right) and then click on the Starlink Passes for All Satellites from a Launch link on the left side of the page. You’ll get a table listing dozens of them. Click any line to see a map of the path that satellite will follow across the sky. If the times are bunched closely all the others will take a similar path, appearing one after another.
During the best passes Starlinks can briefly shine around 1st magnitude — as bright as some of the brightest stars. But some experience temporary flares from reflected sunlight and can equal Jupiter for a few seconds. Because the astronomy community is concerned about the growing “light pollution” from so many satellites SpaceX has been aggressively experimenting with solutions to make them fainter including darkening techniques and shielding them with “sun umbrellas”. Whether these efforts will mitigate the problem of so many imitation stars distracting from the real ones remains to be seen.
*** SPECIAL EVENT: Stuck at home because of COVID-19? You can still enjoy the sky! Join me for the Night Sky Explorer — Launch into Skywatching on Zoom and on Facebook Live brought to you by Voyageurs National Park. I’ll teach basic skywatching techniques, discuss upcoming sights in the night sky and answer your questions during three live, online sessions. The first takes place on Tuesday, April 21 from 4-4:30 p.m. See you then!