Three asteroids: Annefrank, Wild2 and Tempel1

Our solar system has over a million asteroids. These are rocky lumps that orbit the sun. They’re too small to be planets, but are sometimes called ‘minor planets’.

Most asteroids are in a region – the asteroid belt – between the orbits of Mars and Jupiter, but some are in other parts of the solar system.

Asteroids factfileRyugu Vesta
Position from the sunnear Earth orbitin the asteroid belt
Diameter 865 metres530 kilometres
Distance from sun178,500,000 km354,000,000 km
Day length 7.6 hours5.3 hours
Year length 474 days3.63 years
Type of asteroidC-type V-type/minor planet
Surface temperature-50 °C to 60 °C-188 °C to -18 °C
GravityApprox. 0.00013 m/s20.25 m/s2
FUN FACT: Vesta is the second brightest asteroid in the solar system. Ryugu means ‘Dragon Palace’ in Japanese.

Asteroids may seem a bit small and boring compared with colourful and active planets and moons. However, asteroids are rich in a lot of useful minerals (including silver, gold and platinum!) In future, we might send mining missions to them, especially those close to Earth’s orbit like Ryugu.

Asteroid Ryugu as photographed by Japanese mission Hayabusa2
Asteroid Ryugu photographed by Japanese mission Hayabusa2.
Image credit: JAXA, University of Tokyo & collaborators
hayabashu sample capsule in SA desert

This asteroid, Ryugu, was visited by the Japanese Hayabashu 2 Mission in 2019. The probe then returned to Earth with samples taken from the asteroid.

The capsule containing the samples was dropped to Earth as the space probe flew past in December 2020. In the picture, you can see the sample capsule where it landed in the South Australian desert.

Picture Credit: JAXA

The Project Team is fascinated by the appearance of Ryugu and morale is rising at the prospect of this challenge. Together with all of you, we have become the first eyewitnesses to see asteroid Ryugu. I feel this amazing honor as we proceed with the mission operations.

Hyabusu2 Project Manager, Yuichi Tsuda, 25th june 2018


Vesta is an amazing asteroid. If it had been further away from Jupiter, it might have grown into another planet!

Photo of the asteroid Vesta

Do some research to find out all about the amazing history, geography, geology and exploration of Vesta. When you search online for ‘vesta asteroid’, make sure you take information from several different sources, to help you check how accurate each fact is.

Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Make a poster to communicate all your findings about Vesta. Include at least one image of the asteroid, which could be a sketch that you draw, or you might print pictures from the Internet. Then add blocks of text that explain the different things you found out about Vesta.

Hubble image of Ceres, the largest asteroid in the main asteroid belt, compared with four other asteroids (Gaspra, Eros, Ida and Vesta) and Mars.
image credits in picture

You can go to the previous secret pages by clicking the planets below.

The MoonVenusMercury
Moon landing sites for Apollo missions
The SunMars
An image of the Sun in 2018 when it had no sunspots.