Do a simple search for "asteroid" in Google News and the headlines scream at you.
"NASA warns that the 3.2-kilometer planet-killer asteroid is heading for Earth" or "… potential impact date in 2022" or "asteroid tsunami … could devastate the US USA". And of course, "… monster rock to pass the earth at 17,000 mph".
These are just a few of the stories published last week, especially in UK tabloids that really love scary asteroid stories.
If you read beyond the headlines, you'll usually find more accurate information about an asteroid that will definitely not hit Earth anytime soon. That 3km planet killer? Lost us for 1.4 million miles. This is about 6 times farther than the moon. You should literally be more concerned about the moon crashing into your home.
Headlines and misleading stories take advantage of the words scientists use to talk about spatial objects and the connotations that some of those same words have in everyday language.
For example, the phrases "NEO" and "potentially hazardous asteroid" (PHA) are astronomical terms used to categorize objects with very specific definitions. If an asteroid reaches 4.6 million kilometers from Earth and has a certain brightness, it makes the list of PHAs. This is really the way astronomers create a very large catalog of objects worth keeping an eye on. No further assessment is made of each asteroid to determine how "potentially dangerous" it is before assigning this designation.
NEOs fall into an even broader category. If you left Earth and traveled Mars orbit around the sun, stop when you are 85% of the way to the Red Planet, everything between that position and the sun could technically be considered a NEO.
To non-scientists, it may seem strange to call an asteroid that is farther from us than any human has ever traveled "close," but of course it makes sense to deal with the mind-blowing scale of the universe, as astronomers do. The same goes for "potentially dangerous asteroids". It makes sense to call them that, in the context of the immensity of space, although most PHAs are not really a potential risk in our lives.
So the next time you see a headline screaming about how a "giant space rock threatens the earth," you can check out the same sources that I do to determine just how much you should worry. In fact, I will take this particular giant as an example.
Some outlets have already started ringing alarms about the approach of the 2006 SF6 asteroid, which is expected to approach Earth on November 21. It sure sounds like a risky rock coming out of some of the headlines, so I'm # 39; Check out the European Space Agency's risk page.
ESA maintains a list of "all objects for which a nonzero impact probability has been detected".
When I click for the complete list of hazards and search the page for 2006SF6 and its catalog number, 481394, nothing appears. This potential planetary bomber does not appear to have made the list of the 991 most threatening space objects.
Next, I check the public database of close approaches maintained by the Near Earth Study Center at NASA's Jet Propulsion Laboratory. One survey raises the 2006 SF6. It's actually a bit giant, with an estimated diameter between 919 and 2,690 feet (280 and 820 meters).
This skyscraper-sized space rock can do some real impact damage. But its approximate distance is listed as 11.23 lunar distances. This is how it looks: more than 11 times farther than the moon, or about 4.3 million miles (4.3 million kilometers). Sorry, but this giant definitely doesn't threaten the earth.
My point, however, is not that you shouldn't worry about asteroids. So manytell us, the impact threat of a space object is very real. But the main threat comes from objects not yet in our catalogs.
The most significant impact of the last century occurred in 2013, when acreating a shockwave that shattered thousands of windows. This space rock had not been observed before it exploded in the sky.
The technologies and techniques used by astronomers have improved to such an extent that new NEOs are discovered literally every day. This includes some objects really close to Earth, although these tend to be so small that they would probably burn in the atmosphere if they impacted us, as.
But we still have blind spots, as the impact of 2013 demonstrates, so the imperative going forward should not be to scare off some harmless asteroids, but to devote more resources to continuing to scan the sky and complete our catalog so we won't be caught off guard again.