- 3731 - ASTEROIDS - how close are flybys? In September, 2022, NASA's “Double Asteroid Redirection Test’ (DART) mission successfully changed the trajectory of the 525-foot-wide asteroid moonlet Dimorphos which orbits around its 2,560-foot-wide parent rock, Didymos. The success of this first-of-its-kind experiment suggests that as long as we know early enough, we may be able to keep asteroids away from impact.
--------------------- 3731 - ASTEROIDS - how close are flybys?
- The “Dark Energy Camera” at the Observatory in Chile have enabled astronomers to spot three “Near-Earth asteroids” hiding in the glare of the Sun. These near-Earth asteroids are part of an elusive population that lurks inside the orbits of Earth and Venus. One of the asteroids is the largest object that is potentially hazardous to Earth to be discovered in the last eight years.
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- The Dark Energy Camera (DECam) mounted on the Víctor M. Blanco 4-meter Telescope has discovered these near-Earth asteroids hiding in the inner Solar System, the region interior to the orbits of Earth and Venus. This is a notoriously challenging because asteroid hunters have to contend with the glare of the Sun.
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- By taking advantage of the brief yet favorable observing conditions during twilight the astronomers found a trio of near-Earth asteroids. One is a 1.5-kilometer-wide asteroid “2022 AP7“, which has an orbit that may someday place it in Earth’s path.
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- The other two asteroids, “2021 LJ4” and “2021 PH27“, have orbits that safely remain completely interior to Earth’s orbit. 2021 PH27 is the closest known asteroid to the Sun. It has the largest general-relativity effects of any object in our Solar System and during its orbit its surface gets hot enough to melt lead.
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- There are likely only a few near-Earth asteroids with similar sizes left to find, and these large undiscovered asteroids likely have orbits that keep them interior to the orbits of Earth and Venus most of the time. Only about 25 asteroids with orbits completely within Earth’s orbit have been discovered to date because of the difficulty of observing near the glare of the Sun.
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- Astronomers have only two brief 10-minute windows each night to survey this area and have to contend with a bright background sky resulting from the Sun’s glare. Such observations are very near to the horizon, meaning that astronomers have to observe through a thick layer of Earth’s atmosphere, which can blur and distort their observations.
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- DECam is the state-of-the-art instrument one of the highest-performance, wide-field CCD imagers in the world, giving astronomers the ability to capture large areas of sky with great sensitivity.
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- Astronomers refer to observations as ‘deep’ if they capture faint objects. The inner asteroids are rare, and deep images are needed because asteroids are faint and you are fighting the bright twilight sky near the Sun as well as the distorting effect of Earth’s atmosphere.
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- DECam can cover large areas of sky to depths not achievable on smaller telescopes, allowing us to go deeper, cover more sky, and probe the inner Solar System in ways never done before.
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- As well as detecting asteroids that could potentially pose a threat to Earth, this research is an important step toward understanding the distribution of small bodies in our Solar System. Asteroids that are further from the Sun than Earth are easiest to detect. Because of that these more-distant asteroids tend to dominate current theoretical models of the asteroid population.
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- Detecting these objects also allows astronomers to understand how asteroids are transported throughout the inner Solar System and how gravitational interactions and the heat of the Sun can contribute to their fragmentation.
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- Astronomers have discovered a giant asteroid hiding in the glare of the sun that might one day cross paths with Earth. The 0.9-mile-wide asteroid is the largest potentially hazardous asteroid spotted in the past eight years and astronomers have dubbed it a "planet killer" because the effects of its impact would be felt across multiple continents.
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- The asteroid, “2022 AP7“, managed to avoid detection for so long because it orbits in the region between Earth and Venus. Flagship telescopes such as the James Webb Space Telescope and the Hubble Space Telescope never look toward the sun, as the star's brightness would fry their sensitive optics.
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- In 2013, a much smaller asteroid, only 66 feet wide, arrived from the direction of the sun completely without warning. That asteroid exploded above the city of Chelyabinsk in southeastern Russia, shattering windows on thousands of buildings.
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- Only 25 asteroids with orbits completely within Earth's orbit have been discovered to date because of this difficulty of observing near the glare of the sun. The discovery of 2022 AP7, which would be much more damaging than Chelyabinsk if it were to hit Earth, was only possible thanks to the supersentive Dark Energy Camera (DEC) which scans the sky during twilight hours when these asteroids can be detected within two 10-minute periods each day.
- So far we have found two large near-Earth asteroids that are about 0.6 miles across, a size that we call planet killers. There are likely only a few Near Earth Asteroids with similar sizes left to find, and these large undiscovered asteroids likely have orbits that keep them interior to the orbits of Earth and Venus most of the time.
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- Because of its close proximity to the star at the center of the solar system, the asteroid 2021 PH27, experiences the largest effects of general relativity among all solar system objects.
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- According to Albert Einstein's general theory of relativity, massive objects warp spacetime, which can affect the motion of other objects in their vicinity. These effects, which are very minor, can be observed as irregularities in the orbits of planets and asteroids that cannot be explained by Newtonian physics. Luckily, both, 2021 PH27 and the third asteroid, 2021 LJ4, follow orbits that don't intersect with that of Earth.
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- Astronomers are able to calculate asteroid trajectories for centuries into the future and there are currently no known space rocks that should have us worried. And by the time such a rock appears, the global space community hopes to have tools in their hands to protect the planet.
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- November 6, 2022 ASTEROIDS - how close are flybys? 3731
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