Two faces of Eros, western and eastern sides. Picture: NEAR-Shoemaker / Near Earth Asteroid Rendezvous Mission

Asteroids with orbits that bring them within 1.3 AU (121 million miles/195 million kilometers) of the Sun are known as Earth-approaching or near-Earth asteroids (NEAs).
It is believed that most NEAs are fragments jarred from the main belt by a combination of asteroid collisions and the gravitational influence of Jupiter. Some NEAs may be the nuclei of dead, short-period comets. The NEA population appears to be representative of most or all asteroid types found in the main belt.

NEAs are grouped into three categories, named for famous members of each: 1221 Amor, 1862 Apollo, and 2062 Aten.

Amors
Asteroids which cross Mars' orbit but do not quite reach the orbit of Earth. Eros, represented here, is a typical Amor.

Apollos
Asteroids which cross Earth's orbit with a period greater than 1 year. Geographos represents the Apollos.

Atens
Asteroids which cross Earth's orbit with a period less than 1 year. Ra-Shalom is a typical Aten.

Approximately 250 NEAs have been found to date, probably only a few percent of their total population. The largest presently known is 1036 Ganymed, with an approximate diameter of 25.5 miles (41 kilometers).
Estimates suggest at least a thousand NEAs may be large enough (0.6 mile -1 kilometer- or more in diameter) to threaten Earth.

Many bodies have struck Earth and the Moon in the past, and one widely accepted theory blames the impact 65 million years ago of an asteroid or comet at least 6 miles (10 kilometers) in diameter for mass extinctions among many lifeforms, including the dinosaurs. Other theories suggest that the chemical building blocks of life and much of Earth's water arrived on asteroids or comets that bombarded the planet in its youth.

NEAR-Shoemaker landing site. February 2001. Picture: Near Earth Asteroid Rendezvous Mission

Eros is the smallest asteroid represented in 3d model here in SISV, with 33 x 13 x 13 km, is Type S, Amor's group member and orbits between Earth and Mars. It is the 4th visited asteroid and the first one in which a spacecraft has landing. NEAR-Shoemaker lands in February of 2001, from then, Eros has become the more studied asteroid.
Because their name come from the Greek mythology god of love and desire, the craters and areas of the asteroid has been designated with names of the universal literature famous lovers: Don Juan, Don Quixote, Himeros, Cupid, Catherine & Heathcliff, Lolita, and so on.
Eros, with his layered structure of different materials, seemingly comes from a planetoid that has been interrupted in their formation due to collision with other planetoids. Their density is similar to the terrestrial crust.
(see data sheet)

Craters and areas of Eros. Image: Near Earth Asteroid Rendezvous Mission