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Space · Comets and shooting stars

Bennu and Ryugu

Two asteroids visited and touched

Only spacecraft can see it

Bennu and Ryugu
Bennu seen up close: not a rock, but a pile of boulders and gravel.

The numbers

Width of Bennu
1,590ft(484 m)
One spin
4.3hours
One trip around the Sun
438days
Discovered in
1,999
What it is made of
Carbon-rich boulders and gravel

To get an idea

If the Earth takes one year to go around the Sun, Bennu takes one year and seventy-three days.

Fun facts

These are not in the book: there was no room on paper.

  1. Bennu spins on itself in a little over four hours: one of its days is shorter than a morning.

  2. Its orbit crosses the Earth's, and that is why it is classified as potentially dangerous.

  3. Ryugu was visited by the Japanese probe Hayabusa2, which fired a bullet at it to dig.

  4. The samples are opened in sterile rooms, because even a single human hair would spoil the analysis.

  5. Bennu was discovered in 1999 by a program that keeps watch on the asteroids close to the Earth.

Test yourself

The first question is the one printed under the QR code, with the answer the book did not give. The other four only exist here.

Question 1 of 5★ is the one from your book

How wide is Bennu?

Question 2 of 5

What is an asteroid like Bennu really like?

Question 3 of 5

How long is a day on Bennu?

Question 4 of 5

What was found in the samples brought back?

Question 5 of 5

Why does studying these asteroids help keep us safe?

Riddles

I am not one stone, but many stones holding hands. When someone came all this way to touch me, they sank right in. What am I?

I carry the name of a bird that is reborn, I go around the Sun in a little over a year and I pass close to the Earth. A piece of me is now in a laboratory. What am I?

My day lasts four hours, I am a third of a mile wide, and nobody has ever seen me with their own eyes. And yet someone came all the way here to take me. What am I?

Try it yourself

Activity 1

Measure about a third of a mile on a map of your town, starting from your home. That is the whole of the asteroid Bennu.

Activity 2

Set an alarm four hours and twenty minutes apart: that is how long a whole day lasts on Bennu.

The words

sample
A small amount of material collected to study it in a laboratory.
carbonaceous
Dark asteroids rich in carbon, among the oldest in the Solar System.

Sources: Wikidata (Q11558), Wikipedia (101955 Bennu).