Tag: NEAs

Radar images reveal near Earth asteroid to be a contact binary

12:06 pm

Peanut shaped asteroid
Click for original image.

Just after asteroid 1997 QK1 made its first really close pass of the Earth on August 20, 2025, scientists used the Goldstone radio antenna take 28 high resolution images and discovered that the asteriod is peanut shaped, meaning that it is a contact binary of two objects that have fused together.

Those images, cropped, reduced, and sharpened to post here, are shown to the right.

The asteroid is about 660 feet (200 meters) long and completes one rotation every 4.8 hours. It passed closest to our planet on the day before these observations were made at a distance of about 1.9 million miles (3 million kilometers), or within eight times the distance between Earth and the Moon. The 2025 flyby is the closest that 1997 QK1 has approached to Earth in more than 350 years. Prior to the recent Goldstone observations, very little was known about the asteroid.

These observations resolve surface features down to a resolution of about 25 feet (7.5 meters) and reveal that the object has two rounded lobes that are connected, with one lobe twice the size of the other. Both lobes appear to have concavities that are tens of meters deep.

Though this asteroid is classified as potentially dangerous, calculations of its orbit show it poses no threat for the “foreseeable future.”

That it is a contact binary reinforces the present theory that about 15% of all larger asteroids belong to this class.

Leave a comment

Is a recently discovered near Earth asteroid a piece from the Moon?

10:38 am

The uncertainty of science: Researchers now think they have enough information to claim that a recently discovered near Earth asteroid, dubbed Kamo`oalewa, could actually be a piece of the Moon, flung from it during a asteroid impact in the past few million years.

The 2021 study found that Kamo`oalewa’s spectrum was unlike that of other near-Earth asteroids but matched most closely that of the moon. Based on this, the team hypothesized that the asteroid could have been ejected from the lunar surface as a result of a meteoroidal impact.

In the new study, Malhotra and her team wanted to determine the feasibility for a knocked-off piece of the moon to get into this quasi-satellite orbit – a phenomenon that is quite unlikely, Malhotra said. Moon fragments that have enough kinetic energy to escape the Earth-moon system also have too much energy to land in the Earth-like orbits of quasi-satellites, she said.

With numerical simulations that accurately account for the gravitational forces of all the solar system’s planets, Malhotra’s group found that some lucky lunar fragments could actually find their way to such orbits. Kamo`oalewa could be one of those fragments created during an impact on the moon in the past few million years, according to the study.

The scientists add that the asteroid’s solar orbit, which keeps its flying in relative formation with the Earth for millions of years, strengthens this hypothesis.

It must be noted that this remains an unconfirmed hypothesis. A spacecraft would have to visit Kamo’oalewa and obtain samples to study to confirm it.

3 comments

Astronomers discover a new large potentially dangerous near-Earth asteroid

9:36 am

Using a variety of ground-based telescopes, astronomers have discovered three new near-Earth asteroids orbiting the Sun but inside Earth’s orbit, with one of these asteroids having the possibility of one day in the future impacting the Earth.

An international team using the Dark Energy Camera (DECam) mounted on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory in Chile, a Program of NSF’s NOIRLab, has discovered three new near-Earth asteroids (NEAs) hiding in the inner Solar System, the region interior to the orbits of Earth and Venus. This is a notoriously challenging region for observations because asteroid hunters have to contend with the glare of the Sun.

By taking advantage of the brief yet favorable observing conditions during twilight, however, the astronomers found an elusive trio of NEAs. One is a 1.5-kilometer-wide asteroid called 2022 AP7, which has an orbit that may someday place it in Earth’s path. The other asteroids, called 2021 LJ4 and 2021 PH27, have orbits that safely remain completely interior to Earth’s orbit. Also of special interest to astronomers and astrophysicists, 2021 PH27 is the closest known asteroid to the Sun. As such, 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.

You can read their paper here [pdf].

2002 AP7 is the largest such potentially dangerous asteroid discovered in eight years. Its present orbit however never brings it closer to the Earth than 4.4 million miles, and it will be many thousands of years before that orbit might result in an impact. This of course doesn’t prevent foolish mainstream news outlets like the New York Times to label it a “planet-killer.”

The importance of this study however is that it underlines the possibility that there might be other such asteroids lurking close to the Sun that are difficult to spot. This is a blind spot in our asteroid surveys that needs to be eliminated.

14 comments

The known near Earth asteroid catalog now tops 30,000

9:35 am

Chart of NEA's discovered over time

The catalog of known near Earth asteroids that have been identified using a number of survey telescopes in space and on the Earth now totals 30,039. As defined at the link:

An asteroid is called a near-Earth asteroid (NEA) when its trajectory brings it within 1.3 Astronomical Units (au) of the Sun. 1 au is the distance between the Sun and Earth, and so NEAs can come within at least 0.3 au, 45 million km, of our planet’s orbit.

Currently, near-Earth asteroids make up about a third of the roughly one million asteroids discovered so far in the Solar System. Most of them reside in the asteroid belt between Jupiter and Mars.

NEAs are also called NEOs (Near Earth Objects). The chart above, produced by the Center for NEO Studies which tracks these objects, shows the number of NEAs discovered over time.

Of the 30,039 now known, about 1,400 have orbits with “a non-zero” chance of hitting the Earth. None however will do so in the next hundred years at least.

Though the pace of discovery is vastly improving — as indicated by the steep rise in the curve in the graph — only when that curve begins to flatten out will we know that we are getting close to having a more-or-less complete survey of these objects.

5 comments

Tiny asteroid sets record for closest fly-by of Earth

9:10 am

Astronomers using the robotic Zwicky Transient Facility (ZTF) at the Palomar Observatory in California on August 16 spotted a tiny asteroid just after it had zipped past the Earth at a distance of only 1,830 miles, the closest any asteroid has ever been seen to do so without hitting the ground.

Asteroid 2020 QG is about 10 to 20 feet (3 to 6 meters) across, or roughly the size of an SUV, so it was not big enough to do any damage even if it had been pointed at Earth; instead, it would have burned up in our planet’s atmosphere.

“The asteroid flew close enough to Earth that Earth’s gravity significantly changed its orbit,” says ZTF co-investigator Tom Prince, the Ira S. Bowen Professor of Physics at Caltech and a senior research scientist at JPL, which Caltech manages for NASA. Asteroids of this size that fly roughly as close to Earth as 2020 QG do occur about once a year or less, but many of them are never detected.

The ability to spot these things is continuing to improve, though it does not appear they have yet obtained enough information to predict 2020 QG’s full orbit, or when or if it will return.

6 comments

Thursday at the non-existent Lunar & Planetary Science Conference

12:22 pm

Jezero Crater, under theorized ocean

It is now time for today’s virtual report from the non-existent 51st annual Lunar & Planetary Science conference, cancelled because of the terrified fear of COVID-19.

Unlike the previous three days, the bulk of the abstracts for presentations planned for today are more what I like to call “in-the-weeds” reports. The science is all good, but it is more obscure, the kind of work the scientists will be interested in but will generally hold little interest to the general public. For example, while very important for designing future missions, most of the public (along with myself) is not very interested in modeling studies that improve the interpretation of instrument data.

This does not mean there were no abstracts of interest. On the contrary. For today the most interesting sessions in the conference program centered on Mars as well as research attempting to better track, identify, and study Near Earth asteroids (NEAs).

The map above for example shows the location of Jezero Crater, where the rover Perseverance will land in 2021, under what one abstract [pdf] proposed might have been an intermittent ocean. The dark blue indicates where the topography suggests that ocean might have existed, while also indicating its shoreline. If it existed in the past, Perseverance might thus find evidence of features that were “marine in origin.” This ocean would also help explain the gigantic river-like delta that appears to pour into Jezero Crater from its western highland rim.

There were a lot of other abstracts looking closely at Jezero Crater, all in preparation for the upcoming launch of Perseverance in July, some mapping the site’s geology, others studying comparable sites here on Earth.

Other Mars-related abstracts of interest:
» Read more

One comment

Astronomers reduce estimate of still undiscovered dangerous asteroids

11:49 am

Astronomers have now reduced [pdf] their estimate of the number of still undiscovered dangerous Near Earth Asteroids (NEAs) that could impact the Earth from 100 to less than 40.

Observers have been cataloging potentially hazardous asteroids for decades. Based on the number of finds, the area of sky explored, and the limiting brightness our telescopes and cameras can reach, researchers can estimate what fraction of the NEA population has been detected so far and how many more objects lurk undiscovered. Harris has published numerous such estimates over the years. Recently he realized that his estimates have been plagued by a seemingly innocuous but nonetheless consequential round-off error. Once corrected, the estimated number of large (diameter > 1 kilometer) NEAs remaining to be discovered decreases from more than 100 to less than 40.

To put it mildly, there is a lot of uncertainty here. This also reminds me of the cavers’ joke question: “How many miles of unexplored passages does this cave have?”

One comment