Asteroid

Feb 1 2022

La Terra ha un nuovo compagno – e perché questo è eccitante

Non preoccupatevi: questa storia non riguarda di nuovo l'imminente distruzione della Terra. Al contrario: asteroidi come 2020 XL5, scoperto nel 2020, sono eccitanti perché potrebbero fornire intuizioni sul primo passato della Terra. 2020 XL5 è un cosiddetto Trojan, come gli astronomi confermano ora nella rivista scientifica Nature (l'ipotesi esisteva già prima): Un asteroide che accompagna la Terra nella sua orbita. Se si considera solo il sistema dal sole e dal pianeta, ci sono diversi punti in cui le forze attrattive del pianeta e del sole si annullano a vicenda. Questi sono i cosiddetti punti di Lagrange. Gli oggetti che…

42 of the largest asteroids: from spheres to dog bones

Space

Ott 13 2021

42 of the largest asteroids: from spheres to dog bones

More than 650,000 objects orbit in the solar system's asteroid belt between Mars and Jupiter. Astronomers at the European Southern Observatory ESO imaged 42 of the largest in a large-scale effort from 2017 to 2019; the results have now been published. What did they notice? (altro…)

Astrophysics

Giu 24 2020

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

Gen 6 2019

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. (altro…)

Wrong-way driver comes from a different solar system

Space

Mag 22 2018

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…