From Tololo they detect potentially the most dangerous asteroid of the last 8 years

An international team discovered three new near-Earth asteroids (NEAs) lurking in the inner Solar System, the area just before the orbits of Earth and Venus, with the help of the Dark Energy Chamber(DECam) located in the Victor M. Blanco Telescope 4 meters of Cerro Tololo Observatory in Chile, a program of NOIRLab of NSF and AURA. This is a very challenging discovery, as the asteroid hunters had to deal with the intense glare of the Sun to make it.

However, taking advantage of brief but favorable twilight viewing conditions, astronomers found an elusive trio of near-Earth asteroids (NEAs). One of them is a 1.5-kilometer-wide asteroid called 2022 AP7, which has an orbit that could one day put it in Earth’s path. The other asteroids, named 2021 LJ4 and 2021 PH27, have orbits that remain safely inboard of Earth’s orbit. The last of these objects, 2021 PH27, is of special interest to astronomers and astrophysicists, because it is the closest known asteroid to the Sun. As such, it has the effects of general relativity bigger [1] of any object in our Solar System and during its orbit its surface gets hot enough to melt lead.

Our twilight survey is scanning the area within the orbits of Earth and Venus looking for asteroidssaid Scott S. Sheppard, an astronomer in the Earth and Planets Laboratory at the Carnegie Institution for Science, and lead author of the scientific article that describes this job. “So far we have found two large near-Earth asteroids that are about 1 kilometer in diameter, a size we call planet killers.”, he explained.

There are likely only a few NEAs with similar sizes left to find, and these large undiscovered asteroids probably have orbits that keep them inside the orbits of Earth and Venus most of the time. To date, only about 25 asteroids have been discovered with orbits entirely within Earth’s orbit due to the difficulty of observing near the Sun’s glare.Sheppard added.

Discovering asteroids in the inner Solar System is a daunting observational challenge. Astronomers have only two short 10-minute windows each night to survey this area and have to contend with a very bright background sky due to the intense glare of the Sun. In addition, such observations are very close to the horizon, which means astronomers they have to look through a thick layer of Earth’s atmosphere, which can distort their observations. [2]

Despite these difficulties, the discovery of these three new asteroids was made possible by DECam’s unique observing capabilities. The state-of-the-art instrument is one of the world’s highest performing wide-field CCD imagers, giving astronomers the ability to capture large areas of the sky with high sensitivity. When astronomers manage to capture objects with very low illumination they call it “deep” observations. When searching for asteroids within Earth’s orbit, the ability to capture deep and wide field observations is indispensable. DECam was funded by the US Department of Energy (DOE) and was built and tested at DOE’s Fermilab.

Sheppard explained that “large areas of sky are required, because internal asteroids are rare; and deep imaging is needed, because asteroids are faint and you’re fighting against the bright twilight sky near the Sun, as well as the distorting effect of Earth’s atmosphere. DECam can cover large areas of the sky at depths that smaller telescopes can’t reach, allowing us to go deeper, cover more sky, and probe the inner Solar System in ways never before seen.”.

In addition to detecting asteroids that could pose a threat to Earth, this research is an important step in understanding the distribution of small bodies in our Solar System. Asteroids that are farther from the Sun than Earth are easier to detect. So these more distant asteroids tend to dominate current theoretical models of the asteroid population. [3]

Detecting these objects also allows astronomers to understand how asteroids move through the inner Solar System, and how gravitational interactions and heat from the Sun can contribute to their fragmentation.

Our DECam survey is one of the largest and most sensitive searches ever conducted for objects within Earth’s orbit and near the orbit of Venus, and is a unique opportunity to understand what kinds of objects lurk in the inner Solar System.Sheppard concluded.

After 10 years of remarkable service, DECam continues to provide important scientific discoveries while contributing to planetary defense, a crucial service that benefits all of humanity.”, commented the Program Director for NSF’s NOIRlab, Chris Davis.

DECam was originally built to carry out the Dark Energy Study, which was conducted by the DOE and the US National Science Foundation between 2013 and 2019.