Archive for the ‘Planet Earth’ Category


On Brontosauri and Dark Asteroids

March 26th, 2010


Imagine you’re a Brontosaurus with your face in a prehistoric tree top, munching on fresh leaves. Your relatives have ruled planet Earth for more than 150 million years. Huge and strong, you feel invincible.

You’re not.

Fast forward about 65 million years. A creature much smaller and weaker dominates the Earth now, with brains instead of brawn. Its brain is a lot larger than yours relative to its body size – plenty big enough to conceive a way to scan the cosmos for objects like the colossal asteroid that wrought the end of your kind.

The creature designed and built WISE, NASA’s Wide-field Infrared Survey Explorer, to search for “dark” objects in space like brown dwarf stars, vast dust clouds, and your nemesis – asteroids. WISE finds them by sensing their heat in the form of infrared light most other telescopes can’t pick up.

“Our instrument is finding hundreds of asteroids every day that were never detected before,” says Ned Wright, principal investigator for WISE and a physicist at the University of California in Los Angeles. “WISE is very good at this kind of work.”

Visible-light telescopes conducting past asteroid surveys may have missed a large population of darker asteroids that WISE is now flushing out of hiding. Most of the asteroids WISE is finding are in the main asteroid belt between Mars and Jupiter, but a fraction of them are different-they’re the kind of Earth-approaching asteroids that send shivers all the way down a Brontosaurus’ spine.

“WISE has only been in orbit for about three months, but we’ve already found a handful of asteroids classified as ‘potentially hazardous,’ including one seen in 1996 but lost until re-observed by WISE. To be named ‘potentially hazardous,’ an asteroid has to pass within about 5 million miles of Earth’s orbit. One of our discoveries will cross Earth’s orbit less than 700,000 miles away.”

Click here for more

Keep Reading

NASA Projects 2010 to be Hottest Ever

March 25th, 2010

From the Washington Post

The headline to this post may surprise many Washingtonians who are still thawing out from the cold and historically snowy winter. However, not only does a new NASA draft analysis predict that 2010 will likely set a new global temperature record, but it also projects that it is “virtually certain” that a new 12-month running mean global temperature record will occur sometime this year.

Wait a second, you may say. That doesn’t make sense, given the relentless cold thus far in 2010 (at least until the past two weeks), not only in Washington, but also throughout Europe and parts of Asia.

So, where is this forecast coming from?

First, as I detailed last week, the winter of 2009-2010 wasn’t actually very cold from a global perspective. In fact, according to NOAA, the past winter (Dec.-Feb.) was the fifth warmest on record on a global basis.

Second, NASA’s projection, which is in the form of a lengthy and technical paper that is publicly available here, is based on a combination of recent observations and historical evidence. Part of the projection rests on the continued presence of a moderate El Niño, which is a natural climate event characterized by unusually warm water in the equatorial Pacific Ocean. El Niño has long been known to boost average global temperatures by warming the ocean and atmosphere. The all-time record warm year of 1998 (depending on whose statistics you cite) was a year that featured a strong El Niño, for example.

On the other hand, La Niña, which is marked by anomalously cool waters in the equatorial tropical Pacific, can lead to cooler global temperatures.

NASA’s temperature projection is based in part on the knowledge that global surface temperatures tend to lag behind El Niño by about four months. Since El Niño has continued to remain at a moderate strength, and global average temperatures are already running significantly warmer than average, it follows that there is a window of another several months of extra warming within which to set a new record.

You can think of El Niño as adding another few logs on a preexisting fire. Only in this analogy, human activities such as the burning of fossil fuels are also adding their own kindling at the same time.

Click here for more

Keep Reading
1 53 54 55