On November 18, 2019, approximately 19 Starlink satellites passed over Cerro Tololo Inter-American Observatory, disrupting astronomical observations and hindering the science being undertaken in a real, measurable way. If the current plans of SpaceX, OneWeb, and other satellite providers unfold as laid out, the consequences for astronomy will be extraordinary. (CLARAE MARTÍNEZ-VÁZQUEZ / CTIO)

How Can Astronomers Overcome The Damage Being Done By Satellite Mega-Constellations?

Over the coming decades, over 100,000 new satellites are expected.

Ethan Siegel
12 min readJul 15, 2021

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For countless millennia, whenever we were faced with a clear, cloudless, moonless night, all of humanity was able to witness the full beauty of a dark, pristine sky. From any location on Earth, thousands of stars could be seen at once, as well as intricate features in the Milky Way, a handful of other galaxies, and even a number of nebulae, star clusters, and other deep sky objects. With the advent of the telescope — and later, photographic techniques and equipment — those numbers exploded. Our views of the distant Universe were limited only by our technology and the investments we made in them.

But two developments have come along to change that. The first was electric lighting, which led to cities, towns, and now even rural areas frequently emitting more light from the ground than everything in the sky combined. As it stands today, only a small percentage of Earth’s population can see more than a few hundred stars with the naked eye over the course of the night. But the second development — artificial satellites — is extremely recent, only affecting the night sky since the dawn of the space age. At the start of 2019, there were approximately 2,000 active satellites…

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Ethan Siegel

The Universe is: Expanding, cooling, and dark. It starts with a bang! #Cosmology Science writer, astrophysicist, science communicator & NASA columnist.