Bright Lights in the Sky
A batch of 60 Starlink satellites stacked atop a Falcon 9 rocket. Image: SpaceX

Bright Lights in the Sky

08/04/2020Written by Malika Andress

Discover more about SpaceX's Starlink satellite programme.

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We have started getting lots of messages about strange lights in the sky and we think we have the answer for you.
Starlink in the night sky. Image: MovieVertigo

There are many amazing things to see in our clear skies at night right now, including planets, stars, satellites and even a space station, but many people have been asking about a string of bright lights heading over their houses late at night.

If you have seen this series of bright objects in the night sky, it is most likely that you have seen the SpaceX Starlink Satellites.

The satellites are launched in batches of 60 deploying into an orbit about 180 miles above our planet, before thruster firings over the next one to four months move them to an operational altitude of around 340 miles.

An artist’s conception of SpaceX’s Starlink satellites. Illustration: SpaceX
SpaceX Falcon 9 rocket carrying 60 satellites - Nov 2019. Image: SpaceX

Initially the spacing of the satellites and their proximity to the planet’s surface mean they look like a “string of bright pearls” in the night sky, making them very easy to spot. But over time they distance themselves from each other and move further into space, making them less obvious to the casual observer.

With Starlink 6 launching on 18 March 2020 and Spaceflight Now still listing a potential launch of another Starlink batch this month, it is going to become a lot easier to spot these satellites.

Starlink 4 is currently overhead most evenings, however, it has spread out a lot and is no longer as visible. Starlink trails 5 and 6 are still very bright and visible and can be observed in the very early morning.

That said you won’t always be able to see them when they are passing overhead. When we can see them, we call them flares (like the famous Iridium flares you can see from the Iridium communication satellites). This happens when you on the Earth, the satellite and the Sun are positioned in such a way as the Sun is reflected off the satellite and towards you. As a result, many of the passes will be ‘invisible’ to us, even if they are directly overhead. This is also why they suddenly appear and just as suddenly disappear – as soon as the angle is wrong, you can no longer see the reflected light.

What is Starlink?

Starlink is a satellite constellation that eventually will consist of thousands of small satellites in low Earth orbit (LEO), working in combination with ground transceivers to provide satellite Internet access.

SpaceX say that in the long term they intend to develop and deploy a version of the satellite communication system to serve Mars.

In 2016 SpaceX began to seek approval to launch and operate the Starlink satellites and with changes to the original approvals and additional applications, SpaceX currently hold FCC approval to place nearly 12,000 satellites in three orbital shells between 210 miles and 710 miles from the Earth’s surface.

The first two test satellites, known as Tintin A and B, were launched as co-payloads to the Paz satellite on 22 February 2018 and deemed a success.

Successive launches have seen batches of 60 satellites at a time being put into orbit, all within 550 km (340 miles), so easy to view with the naked eye in the night sky.

Although SpaceX claim that the Starlink Satellites will provide broadband internet connectivity to underserved areas of the planet, as well as provide competitively priced service to urban areas, they also plan to sell some of the satellites for military, scientific, or exploratory purposes.

Starlink satellites streak through images captured by a telescope in Chile. Credit: NSF’s National Optical-Infrared Astronomy Research Laboratory / CTIO / AURA / DELVE
Distribution of space debris in orbit around Earth. Image: ESA

The project has not been without controversy are astronomers claim that the number of visible satellites will outnumber visible stars, and that their brightness in both optical and radio wavelengths will severely impact scientific observations. The International Astronomical Union (IAU) and National Radio Astronomy Observatory (NRAO) have released official statements expressing concern on the matter.

The other area of concern is, of course, space junk and the possibility of collisions resulting from placing thousands of satellites in orbit.

Active satellites will use the US Department of Defence’s debris tracking system and onboard autonomous collision avoidance software should allow the satellite to move out of the way of any other satellites or spacecraft.

Failed satellites will deorbit within a few years, however, this still heightens the risk for other satellites and launches from Earth during this period.

There are many websites to help you track Starlink, so you can plan observing sessions, but we really like HEAVENS ABOVE for its ease of use and the fact that you can also use the website to see when other things are passing overhead, including the International Space Station.

If you want to know more about SpaceX‘s Starlink satellites, the video below is from the March 2020 launch of the Falcon 9 from NASA’s Kennedy Space Center in Florida.