Using data from four different ground-based telescopes, astronomers for the first time managed to study the largest near-Earth asteroid (NEA), code-named 2015 TC25. The closest approach of this cosmic body with our planet took place in October 2015, it flew at a distance of only 1,280,000 kilometers from the Earth, which is only a third of the distance from the Moon to the Earth.
An article presented in the Astronomical Journal describes 2015 TC25 as a rare type of magmatic asteroid that has a high concentration of silicates. These types of asteroids form at very high temperatures in a basaltic environment. It is thanks to silicates that 2015 TC25 has very high reflective properties, which makes it one of the brightest near-Earth asteroids. For example, the Moon reflects only 12 percent of sunlight, while the 2015 TC25 surface reflects 60 percent.
“This object is essentially a meteoroid – it looks like a meteorite burning up in the Earth's atmosphere,” said Vishnu Reddy, researcher at the Moon and Planets Laboratory at the University of Arizona, USA, and the main author of the new study.
Raddy's team found that the asteroid completes one on its axis in two minutes, making it one of the fastest-rotating NEA-type objects ever observed by astronomers. It was also noted that asteroid 2015 TC25 itself is a fragment of another asteroid, much larger – 44 Nysa, the size of which is comparable to the size of a multimillion city.
In addition, the 2015 TC25 asteroid differs from others in its structure – it is a monolithic object, and does not consist of many small rocks, like many other, larger asteroids. The surface of the asteroid also leaves questions, as it is not covered with a special layer, reminiscent of regolith dust, like other similar objects.
