AstroKids › Everything in the sky › Sco X-1
X-ray binary · binary with a neutron star

Sco X-1

The brightest X-ray source in the whole sky is here, and you cannot see it at all with your eyes — our air blocks X-rays, so nobody knew about it until we sent detectors above the air in 1962!

🚀 Travel there
Sco X-1 — Drawn, not photographed.

What it is

First cosmic X-ray source found outside the solar system (1962), launching X-ray astronomy.

X-ray binary: A dead star pulling gas off a living one, glowing in X-rays. Every kind of thing there is →

Can you see it?

No. No telescope on Earth will show you this one; it is here to be understood, not seen. It is here because it is worth knowing about — and because leaving it out would make the sky look emptier than it is.

Worth knowing about Sco X-1

On the 100-meter-track scale model of the Milky Way, Sco X-1 would be about 9 meters from the Sun. Light takes 9 thousand years to get here from Sco X-1, so what you are looking at is Sco X-1 as it was 9 thousand years ago.

What it is made of
A close binary where a neutron star pulls gas off a companion star, heating it to blaze in X-rays.
How we know: Since Earth's atmosphere blocks X-rays, first found with a detector on a sounding rocket above the atmosphere; later orbiting telescopes studied its spectrum and flickering.
What makes it worth knowing
Discovered 1962, the first cosmic X-ray source outside the solar system, earning Riccardo Giacconi a share of the 2002 Nobel Prize in Physics.
The numbers
Distance from us~9,000 light-years

Next to it

The Milky Wayspiral galaxyNaked eyeProxima CentauristarWith effortAlpha Centauri A & Bbinary star systemNaked eyeSiriusstarNaked eyeVegastarNaked eyeArcturusstarNaked eye
📖 How the Milky Way fits together

Then go outside

Not this one. But the sky over your head is full of ones you can see, and the Planetarium knows which.

🌙 Plan an evening outside🌌 Everything else in the sky