SpaceX’s unorthodox card-dealing launch of 60 Starlink broadband satellites has led to into an unusual viewing opportunity for skywatchers — and an occasion to wonder about the impact of such mega-constellations on the natural night sky.
A video captured by satellite-watcher Marco Langbroek in the Netherlands sums up the awe. “I could not help shouting ‘OAAAAAH!!!!’ he wrote on his SatTrackCam Leiden blog. “Here is the video I shot, be prepared to be mind-blown!”:
It didn’t take long for Langbroek and other skywatchers to work out the coordinates for the long train of satellites, and to plug those coordinates into online satellite-pass calculators such as CalSky. On Twitter, David Dickinson, author of “The Universe Today Ultimate Guide to Viewing the Cosmos,” started doling out location-specific sighting predictions based on the Orbitron satellite-tracking program.
CalSky automatically picks up your coordinates for satellite sightings, but for those in the Seattle area, the best time to look for the Starlink train passing by tonight is likely to be in the range of 10:50 to 11:10 p.m. PT, going from southwest to northeast. That’s a liberal stretch of time that accounts for a range of locations (say, Port Townsend vs. North Bend), plus uncertainties in the orbital estimates.
There are other passes overnight at around 12:30, 3:50 and 5:20 a.m. PT. The brightness of the satellites is a question mark. Some say they can be seen with the naked eye, while others advise scanning with binoculars. A lot depends on how the satellites pick up the glint of the sun after dusk or before dawn. Tonight Langbroek reported that the satellite train wasn’t as bright as it was the night before.
Speaking of brightness, astronomers and SpaceX fans have already begun the debate over the prospect of having thousands of broadband-beaming satellites in low Earth orbit. The 60 satellites launched this week merely represent the beginning of a campaign aimed at launching as many as 11,000 such spacecraft. And that’s just for SpaceX’s Starlink system. Thousands more could go into orbit for the constellations being contemplated by OneWeb, Telesat, LeoSat Enterprises and Amazon’s Project Kuiper.
Last year, Rocket Lab came in for some grief from astronomers for sending up its “mirror-ball” Humanity Star satellite for a few months of twinkle time in the night sky. This week’s Starlink spectacle renewed the discussion over potential interference with astronomical observations. Even SpaceX CEO Elon Musk joined in:
I know people are excited about those images of the train of SpaceX Starlink satellites, but it gives me pause.
They’re bright, and there are going to be a lot of them.
If SpaceX launches all 12,000, they will outnumber stars visible to the naked eye.
— Alex Parker (@Alex_Parker) May 25, 2019
Not a single one will be visible at night. Just near dusk or dawn, which are not good observing times anyway. Also, only a handful will be around at any given location. It’s just not a problem.
— Daniel Cincunegui (@danielcincu) May 25, 2019
Precisely, sats will be in darkness when stars are visible
— Elon Musk (@elonmusk) May 25, 2019
I get that, but I see ISS ALL THE TIME at night and it has a lower altitude.
— Jim McPherson (@mcjamez) May 25, 2019
ISS is extremely gigantic has lights
— Elon Musk (@elonmusk) May 25, 2019
Hate to disagree with @elonmusk, but: that is true in wintertime, but not in summertime. Then, with altitudes at 550 km, they are visible throughout the night at middle latitudes like Europe. Just like they were last night:https://t.co/xChLDH32uk
— Dr Marco Langbroek (@Marco_Langbroek) May 25, 2019
I’m firmly in the ‘i think they’ll be spaced out enough it won’t really matter’ camp, but that is not true.
Saw them last night at 12:10am in Chicago. (4 hours after sunset) https://t.co/8UkGG8haym
— 📸Trevor Mahlmann (@TrevorMahlmann) May 25, 2019
I’ll try to do a sunlit temporal and spatial analysis tomorrow. I’m guessing we won’t like the number.
— C. G. Niederstrasser (@RocketScient1st) May 25, 2019
In any case, the Starlink satellites shouldn’t be bunched up for long. SpaceX’s plan calls for each satellite to raise its orbit from the deployment altitude of 440 kilometers (273 miles) to the operational altitude of 550 kilometers (342 miles). That happens on a timed basis, every 90 minutes. The idea is that as each satellite raises its orbit, it lags behind the rest of the chain.
Within just a few days, the tightly spaced “train” will turn into a dispersed chain that girdles the globe. And once that happens, chances are that skywatchers and sky-worriers alike will turn their attention to the next batch of Starlink satellites.