The scary, skull-shaped asteroid, which passed by on Halloween 2015, is to approach our planet again. That Halloween night when it passed, astronomers took the opportunity to study its characteristics and learn more about this oddly shaped rock. The asteroid measures between 625 and 700 meters, and it has a three-hour rotation period. It zipped past the Earth at 301,986 miles away, 1.3 times the distance to the moon, while it was discovered on Oct. 10, 2015 with the STARRS telescope in Hawaii.
Many astronomers used their telescopes and other instruments in order to learn more about 2015 TB145, which also includes NASA astronomers who observed it with the Green Bank Radio Telescope in West Virginia and Arecibo Radio Telescope in Puerto Rico. The scientists from Europe, including the researcher Pablo Santos-Sanz from the Institute of Astrophysics of Andalusia (IAA-CSIC), prepared the observing campaigns of the skull-shaped asteroid to learn more about it. He published his findings in the journal Astronomy & Astrophysics.
“It is an Apollo-type near-Earth asteroid (NEA),” Santos-Sanz told SINC. “The proximity of this small object meant greater brightness, so we decided to study it using various observation techniques: on the one hand, we used optical telescopes from the Sierra Nevada Observatory in Granada, the Calar Alto Observatory in Almería and the La Hita Observatory in Toledo; and on the other, we analysed it in the mid-infrared using the Very Large Telescope (VLT) VISIR instrument at the European Southern Observatory (ESO) in Cerro Paranal, Chile.”
“From the observations from Spain, we discovered that this object’s most likely rotation period is 2.94 hours, in other words, this is the approximate length of its day, although we cannot rule out another possibility: 4.78 hours, another solution which is consistent with our optical data,” he added.
From the observations from the mid-infrared from the VLT, authors of the study managed to find the thermal emission of the object. With the use of this information and thermo-physical model, there could be many characteristics of the asteroid yet to be discovered.
“The object measures between 625 m and 700 m, its shape is a slightly flattened ellipsoid, and its rotation axis was roughly perpendicular to the Earth at the time of its closest proximity. Furthermore, its thermal inertia (the amount of heat which it retains and the speed at which it absorbs or transfers heat) is consistent with that of similar sized asteroids.”
The reflectivity of the surface of the skull-shaped asteroid is roughly 5 or 6%. That means that the asteroid can reflect around 5 to 6% of sunlight.
“That means that it is very dark, only slightly more reflective than charcoal,” Santos-Sanz said.
The scientists are hoping to get more data about 2015 TB145 as it zips through our solar system again in November 2018. However, it is worth adding that the asteroid will pass at a further distance from our planet than the last time.
“Although this approach shall not be so favourable, we will be able to obtain new data which could help improve our knowledge of this mass and other similar masses that come close to our planet,” Santos-Sanz said. “It is currently 3.7 astronomical units away from Earth, that is 3.7 times the average distance from the Earth to the Sun,” he points out. “It has a magnitude of 26.5, which means it is only visible from Earth using very large telescopes or space telescopes.”