From ESOCast. Astronomers have accurately measured the size of the remote dwarf planet Eris for the first time. They caught it as it passed in front of a faint star. Eris also seems to be extremely reflective, probably because it is covered in a thin layer of frozen atmosphere.
Occultations are rather like eclipses —the background star disappears behind the object and reappears on its other side. As viewed from Earth, the brightness of the background star suddenly drops and then returns equally suddenly to its previous level. By looking at these two events, astronomers can measure the size and shape of the occulting foreground object. If they also know the mass of this object they can then determine its density.
The occultation technique has now enabled astronomers to learn a lot more about the dwarf planet Eris. Eris was identified as a large object in the outer Solar System in 2005. Its discovery was one of the factors that led to the creation of a new class of objects cal... more
Occultations are rather like eclipses —the background star disappears behind the object and reappears on its other side. As viewed from Earth, the brightness of the background star suddenly drops and then returns equally suddenly to its previous level. By looking at these two events, astronomers can measure the size and shape of the occulting foreground object. If they also know the mass of this object they can then determine its density.
The occultation technique has now enabled astronomers to learn a lot more about the dwarf planet Eris. Eris was identified as a large object in the outer Solar System in 2005. Its discovery was one of the factors that led to the creation of a new class of objects cal... more
