2019 LD2: the unruly comet Astrophysics

2019 LD2: the unruly comet

Asteroids and comets are generally thought to be different classes of celestial objects. But is the strict distinction really justified? The interstellar visitor ʻOumuamua, for example, was initially thought to be a comet, but didn’t develop either a coma or a tail and was then classified as an asteroid. In the meantime, its trajectory has been calculated so precisely that it must have lost mass – which means it is definitely a comet. The object 2019 LD2 discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS) of the University of Hawaii also appears to be some sort of hybrid.…
Way, way out there: “Farout” is a pink dwarf planet Space

Way, way out there: “Farout” is a pink dwarf planet

It is approximately 500 kilometers big (roughly the size of Saturn’s moon Enceladus), has a surface that appears to be pink from a distance (typical for an ice-rich object), and takes about 1000 years to make one orbit around the Sun. That’s all astronomers know about the dwarf planet nicknamed “Farout,” whose discovery was recently announced. The object’s actual designation is 2018 VG18; it got its nickname because it was discovered so far out from the Earth. (more…)
Wrong-way driver comes from a different solar system Space

Wrong-way driver comes from a different solar system

More than a year ago, the asteroid 2015 BZ509 made headlines among astronomers, because it is circling our Sun as a wrong-way driver – its direction of motion is opposite that of all the planets and most other objects. To make this work, this asteroid selected an especially clever orbit, a trisectrix, which is apparently stable over the long term. Even a year ago, the following was being still said: “Nobody knows exactly where 2015 BZ509 comes from. It might be a former comet that, however, is no longer active.” That wasn’t enough for two astronomers. The researchers simulated the…