Eros is the first asteroid discovered whose orbit is mostly within the orbit of Mars and which passes the orbit of Earth.
The shortest distance it has reached from the Earth was 23 million km in 1932 and astronomers took advantage of this approach to determine the value of the astronomical unit (ua) which is 140 million km, the average distance from the Earth to the Sun.
At the point closest to the sun (perihelion) Eros’ orbit is very close to Earth’s, but does not cross it.
Eros was discovered on the night of August 13, 1898, independently by three astronomers: Gustav Witt, who named him), F. Linke in Berlin and by Augusto Honorato Pedro Charlois from Nice.
The asteroid Eros has an elongated shape. It measures 33x13x13 km.
In February 1996, Eros was the first asteroid to be orbited by a space probe, the NEAR Shoemaker, allowing an asteroid to be seen up close.
On February 12, 2001, the NEAR mission collided on the surface of Eros, surviving well enough to send an analysis of the composition of the asteroid’s surface from there.
The probe continued to transmit data from the asteroid’s surface until February 28, 2001.
The NEAR probe allowed scientists to discover that Eros is a rocky fragment, which formed during the first years of our Solar System.
Scientists who have studied it have found no sign that it has ever melted in its entire history of possibly 4.5 billion years.
Eros makes one complete revolution around its axis in 5 hours 16 minutes and completes one revolution around the Sun in 642 days. It is 180 million kilometers from Earth.