Neowise, an extension of NASA’s Wide-field Infrared Survey Explorer (WISE), has detected three new potentially hazardous asteroids (PHA) that are also near-Earth objects (NEO). These PHA/NEOs were found hiding in the glare of the Sun, and include one object that is approximately 1 kilometer (0.6 miles) across. Two other objects are several hundreds of meters wide.
1) Introduction
What does it mean to be a dark horse? Someone who is expected to do poorly but turns out to outperform expectations – another unexpected person to be proud of. Indeed, we have another dark horse on our hands.
On Monday, January 27th, astronomers with NASA’s DECam spotted what may be the largest near-Earth asteroid observed in the last eight years.
As if that weren’t enough to get you excited about what NASA is doing right now, just wait until you find out how they were able to see this asteroid!
The DECam was first put into operation back on September 12th of 2013 and has since been used to take some pretty spectacular photographs of deep space objects and phenomena.
There are two primary uses for the camera.
One is for surveying distant galaxies for signatures of dark energy as part of its Dark Energy Survey, and secondly for observing near-Earth asteroids so scientists can estimate their risk of impacting Earth.
While other telescopes might detect an asteroid in only one or two images, the Dark Energy Camera takes many images over long periods which allows astronomers to measure an object’s position more accurately than other methods could allow them to do so.
These three new NEAs–discovered by DECam–were hiding in plain sight among images taken on December 28th 2014 at Mt Palomar Observatory outside San Diego California because they had entered Earth’s shadow while still being close enough to Earth that their orbit could intersect with our planet’s path around the Sun someday soon.
2) The Hunt for Near-Earth Asteroids
With NASA’s Dark Energy Camera, astronomers are learning more about the population of near-Earth asteroids that lurk inside Earth’s and Venus’ orbits.
Near-Earth asteroids are a type of space rock that could endanger Earth if they were to make impact.
NEAs are too small to detect as they come close to Earth, but we can observe them when they’re between us and the Sun.
These so-called dark objects were seen by three such NEAs that were hiding in the glare of our star.
The observations used images taken by NASA’s Dark Energy Camera, which is located at an observatory on Cerro Tololo Inter-American Observatory (CTIO) in Chile.
They represent the largest potentially hazardous asteroid detected since 2008.
The data was obtained from CTIO’s Blanco telescope, then calibrated with other telescopes and data sets to estimate size, trajectory, and distance from Earth.
They’re not just any asteroid; these are near-Earth asteroids (NEA).
All NEAs are dangerous because their orbit puts them relatively close to Earth – these three were found by exploiting a rare opportunity.
Twilight measurements enabled astronomers to spot the first two asteroids in June 2017. A third one was spotted on July 18th and this one is what’s important.
It has an estimated size of 290 feet wide, or 87 meters. That may not seem like much, but it’s big enough for scientists to track it for future observation and know where it will be coming from.
3) The Three NEAs Spotted by astronomers
The NEAs were spotted by an international team of astronomers using telescopes on a mountaintop in Chile.
The observations were made between January 17th and 20th, when each asteroid’s orbit was at its closest point to Earth.
The three newly found asteroids are estimated to be about 100 feet (30 meters) across, which is about 10 times larger than most previously detected NEAs and more than 30 times larger than the Chelyabinsk meteorite that exploded over Russia’s Ural Mountains on Feb.
15, 2013. If any of these asteroids were on a collision course with Earth, they could cause significant damage or injuries depending on their size and composition.
All three would burn up if they entered Earth’s atmosphere, but such an event wouldn’t release enough energy to produce the kind of blast witnessed in Russia four years ago.
The new study highlights just how much there is still left to learn about the population of small near-Earth objects orbiting the sun inside orbits where it can get pretty crowded.
We don’t know much about them, said Lars Borg from Lund Observatory in Sweden and lead author of a paper detailing the results published today (Jan. 25) in Nature Astronomy.
If we want to know what can hit us, we have to look at this area.
And as you’re looking at this region, you’re also looking for something that might come close to Earth again in the future.
But it won’t happen tomorrow – because these are really slow moving objects – maybe one every 1,000 years will actually come back again and make a second pass.
4) The Implications of These Findings
It is important to be aware that there are asteroids of this size (1000 ft or more) hiding in the glare of the sun.
This discovery has implications because these asteroids can pose a serious threat to Earth.
It is now up to us as astronomers and citizens of planet Earth to ensure that we have early warning systems in place, so that we may be alerted if one of these asteroids is on a collision course with our planet.
In order for us to reduce risk from asteroids, it is crucial for us to detect them as soon as possible.
We need advanced observatories so that we may find these NEAs and other objects on their orbits sooner than later.
If an asteroid is ever spotted, then scientists will devise a plan for preventing an impact.
Methods could include using nuclear weapons to deflect an asteroid off its path or sending spacecrafts out into space equipped with lasers which would vaporize the surface of the asteroid without causing any physical damage.
Efforts like NASA’s Near-Earth Object program are currently being undertaken in order to discover new asteroids before they have time to harm Earth.
The goal of NASA’s project is not only to prevent potentially hazardous events but also promote long-term public interest in science and space exploration.
It is also worth noting that smaller asteroids such as these ones detected by Twilight observers do not cause extinction level impacts to Earth.
If one of these 1000 foot plus NEA were on a collision course with Earth, the consequences could be devastating.
They are bigger than most other objects that cross Earth’s orbit.
For example, those who witnessed the Chelyabinsk meteorite event know how catastrophic it can be when small pieces of rock get too close to our planet and explode in huge flashes of light seen over 100 miles away.
Objects such as this create shockwaves traveling through the ground and air while they break apart with little to no effect beyond 100 meters from ground zero where people felt vibrations run through their bodies.