Eros is an asteroid in a high elliptical orbit around the Sun. It was discovered in 1878 and it is 33 km wide.
Back in the late 1920's, astronomers around the world knew that Eros will be again close to the Earth in 1931. They made calculations of the star field where Eros will transit to attempt to calculate the distance to Eros. This was a large undertaking as precise measurements of the stars needed to be done as well as of Eros.
Simultaneous observations of Eros from different parts of the world provides the necessary data to calculate distances using parallax.
Three weeks ago, Eros was in opposition again at a distance of 0.2 AU from Earth. Astronomers around the world are attempting a re-enactment of the observations and calculations done back in 1931. Not only will we be able to determine the distance to Eros, but we could estimate with these measurements the size of our Solar system. The animated image was captured from VAO in Webster, NY and shows (roughly), Eros transiting at a speed on the plane of the sky of 7 arc seconds per minute.
