Ryugu

Ryugu is darker than a lump of coal — it reflects almost none of the sunlight that hits it! Japan's Hayabusa2 brought a few grains of it home.

🚀 Travel there

What it is

Dark diamond-shaped rubble-pile asteroid sampled by Japan's Hayabusa2.

Asteroid: Rock or metal left over from building the planets. 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 Ryugu

Ryugu is about as wide as nine football pitches laid end to end. In weight, far too light to meaningfully compare to Earth. About the same neighborhood as Earth — another 'near-Earth asteroid'. Sunlight takes 10 minutes to reach Ryugu — on average, because that distance changes as it goes round. Its year: about one and a third years. Its day: 7.63 hours.

Its surface: Dark, diamond-shaped rubble pile, similar in makeup to Bennu.
The machines we sent: JAXA's Hayabusa2 touched down twice — even firing a copper 'bullet' to dig up a fresh underground sample — and returned it to Earth in 2020.
What makes it worth knowing: The 2020 returned sample contained amino acids and vitamin B3, and later all five DNA/RNA nucleobases together for the first time ever from a space sample.

How did anyone measure the Earth in the first place?

The numbers

Across	1 km
Distance from the Sun, on average	1.19 AU ~178 million km · sunlight takes 10 minutes
Once round its orbit	1.3 Earth years
One day there	7.6 hours

What it belongs to

☀️ Everything the Sun holds, in one place 📖 How the solar system 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