2023 JL1: Bus-Sized Asteroid Approaching Earth Today, Says NASA

Asteroids approaching Earth always make headlines because a collision with one could result in a massive disaster for human life. This time, scientists at the American space agency NASA have warned about a bus-sized asteroid that is expected to make its closest approach to Earth today.

According to NASA's Asteroid Watch page, the 39-foot bus-sized Asteroid 2023 JL1 will pass by Earth at a distance of 2,490,000 kilometres. It is travelling at a speed of 26,316 kilometres per hour.

NASA has also warned about two other asteroids - 2023 JO1 and 2023 JD2. While the former is the size of a house (46 feet) and will make its closest approach to Earth at 2,990,000 km, the latter is aeroplane-sized (200 feet) and will pass by Earth at a distance of 5,630,000 km. 

Notably, NASA's dashboard tracks asteroids and comets that will make relatively close approaches to Earth. The dashboard displays the date of the closest approach, approximate object diameter, relative size and distance from Earth for each encounter. It tracks asteroids that are within 7.5 million kilometres of Earth.

Some 30,000 asteroids of all sizes -- including more than 850 larger than a kilometre wide -- have been catalogued in the vicinity of the Earth, earning them the label "Near Earth Objects" (NEOs). None of them threatens the Earth for the next 100 years.

According to NASA, asteroids are left over from the formation of our solar system. Our solar system began about 4.6 billion years ago when a big cloud of gas and dust collapsed. When this happened, most of the material fell to the centre of the cloud and formed the sun. Some of the condensing dust in the cloud became planets.

Not all asteroids are the same size and shape. Because asteroids are formed in different locations at different distances from the sun, no two asteroids are alike. Asteroids aren't all around like planets and have jagged and irregular shapes.  Most asteroids are made of different kinds of rocks, but some have clays or metals, such as nickel and iron.