SpaceX's Starlink a WORSE threat to astronomy than light pollution

Satellite mega-constellations including SpaceX’s Starlink are now a WORSE threat to astronomy than light pollution, experts warn

  • The International Astronomical Union (IAU) launched a new constellation center
  • Its goal is to connect astronomers, megaconstellation providers and regulations 
  • They want to encourage firms such as SpaceX to minimise impact of satellites
  • This could include painting them to make the satellites less reflective of sunlight
  • They are also working on software for observatories to counter constellations 

Mega-constellations of low Earth orbit satellites, including SpaceX Starlink and Amazon Kuiper, are a ‘worse threat to astronomy than light pollution’, experts warn.

There are 2,000 SpaceX Starlink satellites currently in space, with as many as 42,000 planned over the coming years, and it is just one of a number of firms looking to fill low Earth orbit with spacecraft, to provide fast, space-based internet.

These networks of tens to thousands of spacecraft have proven controversial, especially among astronomers, as they leave streaks in images of space. 

To combat the problem, and work with the satellite industry on a solution, the International Astronomical Union (IAU) has launched the Center for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference.

Piero Benvenuti, IAU General Secretary and director of the new centre, said these mega-constellations are the biggest threat facing modern astronomy.

He plans to bring together astronomers, mega-constellation operators, and regulators to find solutions, that could include software changes at observatories, and adjustments to satellites to reduce the impact they have on observations.

Mega-constellations of low Earth orbit satellites, including SpaceX Starlink and Amazon Kuiper, are a ‘worse threat to astronomy than light pollution’, experts warn 

An image of the NGC 5353/4 galaxy group made with a telescope at Lowell Observatory in Arizona, US. The diagonal lines running across the image are trails of reflected light left by Starlink satellites soon after launch in 2019

While SpaceX is the most high profile of the mega-constellation providers, it isn’t alone in filling low Earth orbit with spacecraft – many of which reflect light to Earth.

The first 60 Starlink satellites were launched in 2019, and there are now more than 2,000 in low Earth orbit, with dozens going into space every month.

Other firms, such as Amazon Kuiper and OneWeb, will significantly increase the total number of satellites, and China plans a network of 13,000 spacecraft.

The aim of these networks is to provide satellite internet to rural locations, where fiber isn’t viable, with latency speeds in the tens of milliseconds, instead of hundreds of milliseconds found through traditional, geosynchronous satellite internet.

SpaceX has made some effort to tackle the problem, through the DarkSat and the VisorSat, coatings and shielding to reduce a satellite’s glow when viewed from Earth.

Other firms, such as OneWeb, operate at a higher orbit – about 750 miles – than SpaceX, which places its satellites about 350 miles above the Earth.

The new center will be run jointly by the UK-headquartered Square Kilometer Array Observatory organization (SKAO) and the US National Science Foundation’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab).

Both of these organizations are developing next-generation telescopes that will have their observations compromised by satellite interference.

The streak from a Starlink satellite appears in this image of the Andromeda galaxy, taken by the Zwicky Transient Facility, or ZTF, during twilight on May 19, 2021. The image shows only one-sixteenth of ZTF’s full field of view


  • Rocket launches since 1957:  5450
  • Number of satellites in orbit: 8950 
  • Number still in space: 5000 
  • Number still functioning: 1950
  • Number of debris objects: 22300
  • Break-ups, explosions etc: 500 
  • Mass of objects in orbit: 8400 tonnes 
  • Prediction of the amount of debris in orbit using statistical models 
  • Over 10cm: 34 000 
  • 1cm to 10cm: 900 000 
  • 1mm to 1cm: 128 million 

Source: European Space Agency 

SKAO is building the world’s largest radio telescope array on two sites in Australia and South Africa ,and NOIRLab’s Vera C. Rubin Observatory is launching in Chile.  

SKAO has been designed to measure the faintest radio signals coming from distant stars, galaxies and even exoplanets – but it will be partially blinded by constellations.

Vera C Rubin Observatory, will carry out a 10-year Legacy Survey of Space and Time (LSST), delivering a 500 petabyte set of images of the entire night sky. 

‘In the past, the main source of interference was the light pollution by urban illumination, the so-called artificial light at night,’ Benvenuti said in a statement. 

‘But more recently, the impact of the large constellations of communication satellites became a more serious concern because of their ubiquitous invasiveness.’

Astronomers could avoid the impact of urban illumination by putting their telescopes in ever more remote locations on Earth – such as deserts of Chile, Australia and South Africa, but they can’t avoid trains of satellites.  

‘By the end of the decade, more than 5,000 satellites will be above the horizon at any given time,’ Connie Walker, a scientist at NOIRLab said.

‘At a typical dark sky observatory location, a few hundred to several thousand of these satellites will be illuminated by the sun.’

They will be detectable even by the smallest optical and infrared telescopes, causing problems for astronomers using the largest and smallest observatories.

The telescopes most hit will be those designed to look for the most distant and dimmest stars and galaxies, as the reflected light from satellites will brighten up the night sky enough to increase the light reaching the telescopes.

SpaceX has been launching an increasing number of internet satellites since 2018, with over 2,000 now in low Earth orbit, about 340 miles above the planet

Last year the IAU began discussions with the United Nations over the need to protect the ‘pristine night sky’ from the ever increasing number of satellites.

‘These trains are nice and impressive, but do we really want to see them everywhere?’ Thomas Schildknecht said on April 20, 2021. 

‘Do we want to see them in the Australian outback? In Antarctica? Or in the very dark regions of Chile? Probably not.’ 

A recent study by the Zwicky Transient Facility in San Diego found that Starlink satellites disrupted a fifth of images. 

This facility is designed to watch for asteroids, and they predict that if 10,000 satellites are in low Earth orbit, every image will contain at least one streak. 

However, it isn’t all bad, as each streak accounts for just one tenth of one percent of the pixels visible in a full ZTF image, having less of an impact than a cloudy sky.


Elon Musk’s SpaceX has launched more than 1,800 of its ‘Starlink’ space internet satellites into orbit.

They form a constellation designed to provide low-cost broadband internet service from low Earth orbit.

The constellation, informally known as Starlink, is under development at SpaceX’s facilities in Redmond, Washington.

Its goal is to beam superfast internet into your home from space.

While satellite internet has been around for a while, it has suffered from high latency and unreliable connections.

Starlink is different. SpaceX says putting a ‘constellation’ of satellites in low earth orbit would provide high-speed, cable-like internet all over the world.

The billionaire’s company wants to create the global system to help it generate more cash.

Musk has previously said the venture could give three billion people who currently do not have access to the internet a cheap way of getting online.

It could also help fund a future city on Mars.

Helping humanity reach the red planet is one of Musk’s long-stated aims and was what inspired him to start SpaceX.

The company has previously filed plans with the Federal Communications Commission (FCC) to launch 4,425 satellites into orbit above the Earth — three times as many that are currently in operation.

‘Once fully deployed, the SpaceX system will pass over virtually all parts of the Earth’s surface and therefore, in principle, have the ability to provide ubiquitous global service,’ the firm said.

‘Every point on the Earth’s surface will see, at all times, a SpaceX satellite.’

The network will provide internet access to the US and the rest of the world, it added.

It is expected to take more than five years and $9.8 billion (£7.1bn) of investment, although satellite internet has proved an expensive market in the past and analysts expect the final bill will be higher.

Musk compared the project to ‘rebuilding the internet in space’, as it would reduce reliance on the existing network of undersea fibre-optic cables which criss-cross the planet.

In the US, the FCC welcomed the scheme as a way to provide internet connections to more people.

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