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At Phys.org: Astronomer suggests it is time to look for near-Earth asteroids in the direction of the sun


Bob Yirka writes:

Scott Sheppard, an astronomer with the Institute of Astronomy at the University of Hawaii, has published a Perspective piece in the journal Science suggesting that it is time for the space science community to take a closer look at near-Earth objects (NEOs) that lie in the direction of the sun. In his paper, he notes that the technology now exists to look for and find such NEOs, at least during the twilight hours.

Credit: CC0 Public Domain

As Sheppard notes, most space gazing is fixed at the dark night sky, when the sky is not overwhelmed with light from the sun. But as a result, space scientists have ignored the NEOs that orbit between Earth and the sun. And that could lead to trouble, since one or more of them could be on a path that leads to them crashing into Earth.

Scientists are not completely ignoring NEOs that exist in the sun’s glare, of course. Sheppard notes that many of them have been discovered recently. But he says that more such studies are required to learn more about them. He points out that one team recently discovered an asteroid with an orbit inside of Venus’s orbit and another that has the shortest trip around the sun. He also notes that new facilities have the capabilities needed to study such NEOs, such as the Zwicky Transient Facility in the U.S. and the NSF Blanco-4-meter facility in Chile. The latter even has a Dark Energy Camera that can be pointed closer to the sun.

NEOs that orbit the sun inside of Earth’s orbit have been categorized based on their orbital positioning—if they travel inside of Venus’s orbit, for example, they are called Vatiras. Additionally, Sheppard notes that their numbers remain relatively constant, which is somewhat of a surprise. Based on computer models and the number of such objects that strike the Earth, the moon, or other celestial bodies, their numbers should be dropping. That they are not suggests that they are being replenished somehow. He thinks efforts should be made to find out where those other NEOs are coming from, and why.


That no asteroid impacts have devastated human civilization in historical memory doesn’t mean that it won’t happen in the future. We can be thankful that we live in a window of time that has been free from such disasters.

Ed at 10, A miscommunication. Sadly, the internet provides no actual way to get to know someone. relatd
Relatd @9: Huh? what are you getting at? What "wild assumption"? I was merely questioning how they could know that the number of NEO's is "relatively constant". Yes, asteroids have impacted the Earth for a long time, but does anyone have a credible timeline for how many impacts per millennium over the past million or so years? That would be needed to tell whether the number is increasing or decreasing. If you know of some way to demonstrate (especially without assumptions!) the changing (or steady) rate over time, I'd be pleased to see it. You seem to be jumping into contrary mode by adding extraneous things (your own assumptions?) to what I actually wrote. I said nothing of planetary defence, and last time I checked, a "few" was more than two. If you didn't have an answer to my honest question, that was OK. I just thought some UD reader might know more about it than I do. Pax, Ed. Fasteddious
Fasteddious at 8, You make your own wild assumption. Asteroid impacts have been a big concern for longer than the past two decades. And there is no easy, quick answer to your question. Planetary defense has been worked out. To know more you are going to have to do the research. Actual research that does not involve assumptions. https://cneos.jpl.nasa.gov/ relatd
The article says, "their numbers remain relatively constant". How on Earth do they know that? We've only been looking for NEO's seriously for the past few decades, an instant in geological time. And counting craters of uncertain age elsewhere is a poor proxy for the rate of NEO generation. Does anyone know how they can make that statement? Fasteddious
But we have had impacts more recent than Chicxulub 66 million years ago. There's Meteor Crater in AZ, for example. But even more recent are the 12,000 BC impact that annihilated all North American megafauna, such as horses. Read "Cycle of Cosmic Catastrophes" by Firestone. Plato tells us in the Critias of a cycle of ~1600 years that brought fire and floods from the heavens. The Genesis Rabbah (a rabbinic commentary on Genesis) speaks of a similar 1500 year cycle that shakes the firmament. We are way overdue. Robert Sheldon
The problem with NEOs is not so much spotting them as with spotting them in time. If we spot one a few years before it is predicted to hit Earth then we have a chance to mount an effective response. If we don't see it until it's only a few weeks or months out then, as things stand, we probably won't have enough time to do anything. Seversky
https://www.jpl.nasa.gov/asteroid-watch relatd
You just put a satellite on the sun side opposite of Earth, looking out. Then you put one the left and right sides of the sun. I’m sure very smart people did not miss this detail.
I'm sure they didn't and we already have solar observatories. The other detail they didn't miss is that any object approaching from sunward will have its dark side towards us. Spotting the dark side of an approaching asteroid against the darkness of space is no easy matter. Seversky
Seversky at 2, You just put a satellite on the sun side opposite of Earth, looking out. Then you put one the left and right sides of the sun. I'm sure very smart people did not miss this detail. relatd
I wish I could remember who it was but a few years back I read a comment from an astronomer to the effect that while NEOs coming from outside Earth's orbit were obviously a concern, what really scared him were NEOs coming from sunwards because we just wouldn't see them coming. Seversky
"window of time"? The last asteroid impact was 66 million years ago. I'm confident the very wealthy have paid for an effective means of destroying large asteroids in space before another gets in striking range. relatd

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