27-06-2025
Five famous space rocks
Asteroids are small, rocky objects that orbit the Sun. They are much smaller than planets and are sometimes called minor planets or planetoids. Most asteroids are found in the asteroid belt, a region between the orbits of Mars and Jupiter. Why do we have a special day to celebrate space rocks? On June 30, 1908, a massive explosion over Tunguska in Siberia flattened approximately 2,150 of forest. This was attributed to the airburst of a small asteroid or comet. In December 2016, the UN General Assembly officially designated June 30 as International Asteroid Day to educate the public about asteroid impact hazards. Let us now look at five famous asteroids.
Ceres
The largest object in the asteroid belt between Mars and Jupiter, Ceres holds the distinction of being the first to be discovered, in 1801 by Giuseppe Piazzi. With a diameter of approximately 940 km, it is so massive that it is now classified as a dwarf planet. Ceres has a rocky core and a mantle of water ice. Observations suggest there may be briny water below its surface. Scientists are especially interested in Ceres because it may hold important clues about the early solar system and the origin of water on Earth.
Vesta
Also known as 4 Vesta, this was formed about 4.56 billion years ago, shortly after the solar system began. This makes it one of the earliest bodies to solidify from the solar nebula. Vesta's age and structure provide crucial insights into planetary formation. NASA's Dawn mission visited the asteroid in 2011 to study this remarkable relic and understand how the early solar system evolved.
Eros (433 Eros)
Discovered in 1898, Eros is a near-Earth asteroid (NEA) about 34km long. It was the first to be orbited and landed on by a spacecraft: NEAR Shoemaker in 2000–2001. Eros is classified as an S-type asteroid, composed primarily of silicate rock. Its elongated shape and cratered surface provide valuable information about asteroid geology.
Itokawa
Itokawa is a small peanut-shaped near-Earth asteroid (NEA), just 535m in length. It became famous after Japan's Hayabusa mission successfully collected samples from its surface in 2010; the first such mission in history. Itokawa is a 'rubble pile' asteroid, composed of loose rocks held together by gravity, rather than a solid monolith.
2015 TC25
The smallest known asteroid is 2015 TC25, discovered in October 2015, and measures only about two meters in diameter; roughly the size of a small car. It is an E-type asteroid, known for its bright, reflective surface, and spins incredibly fast, completing one rotation every two minutes. Despite its tiny size, it was detected using ground-based telescopes, highlighting significant advances in observational astronomy.
