Comet Lulin

Comet Lulin, is zooming past the Earth this week on its whirlwind tour of the inner solar system. Some comets are in orbits that periodically bring them back to the inner solar system, but if astronomers are correct, Comet Lulin has never been here before and will never be back again. Better enjoy it while it’s here.

What are comets? Astronomers think of them as the frozen leftovers from the formation of our solar system nearly five billion years ago. A typical comet is about 10 miles across and made primarily of frozen water and other exotic ices. Unlike the planets, whose orbits are nearly circular, comets are in highly elongated orbits that carry them from the cold recesses of the outer solar system into the hot inner solar system during a period of hundreds, thousands or even millions of years. It is only when a comet enters the inner solar system that it swells and grows its characteristically beautiful tail. The pressure of sunlight and the solar wind blows the comet’s vapors and dust away from the sun and out of the solar system.

Everything about Comet Lulin seems backwards. It orbits in the same plane as the major planets, but in the opposite direction. And rather than pointing away from the sun, its dust tail seems to point toward the sun. Comets orbiting the sun backwards are not all that unusual. In fact, the most famous of all comets, Halley’s Comet, orbits backwards. What is unusual about Comet Lulin is that it does so in the same plane as the planets, like a fish swimming upstream. Consequently, when it passes only 38 million miles from Earth this morning, Earth and comet will pass each other at the dizzying speed of 140,000 mph. After that, Comet Lulin will quickly fade into the distance. Its quirky anti-tail that points toward the sun is really an optical illusion caused by our line-of-sight view straight down the tail. Lulin’s sunward-pointing anti-tail is, in reality, curving off behind the comet, but it appears to project itself out in front. In 1957, Comet Arend-Roland also displayed an unusual anti-tail toward the sun.

I love comet-watching for two reasons. First, comets bring excitement to a sky in which not much changes except during centuries or millennia. Second, every comet is different and has its own unique personality. One never quite knows what to expect when a new comet is discovered.

Such was the case when astronomers at China’s Lulin Observatory discovered this most recent comet in 2007 while still far from the sun. After a year and a half of waiting, Comet Lulin now is bright enough to be spotted with the unaided eye from dark sky locations. It sailed past the bright planet Saturn earlier this week, and now Comet Lulin will be cruising through the stars of Leo the Lion, including a close pass by Leo’s brightest star Regulus on the night of Feb. 27. This comet is no Hale-Bopp, however, so use binoculars to help you spot the green fuzzball and its short, spiky tail. For finder charts, updates and a Comet Lulin image gallery, check out the NASA-sponsored Web site Space Weather. You might even spot some of my comet images there. Happy comet-watching.

Technorati Profile

Earth is warming faster

Earth is warming faster than scientists have predicted, in part because industrial greenhouse gas emissions have increased, U.S. scientists say.

Scientists say higher temperatures are triggering responses in ecosystems, The Washington Post (NYSE:WPO) reported Sunday.

“We are basically looking now at a future climate that’s beyond anything we’ve considered seriously in climate model simulations,” said Christopher Field, founding director of the Carnegie Institution’s Department of Global Ecology at Stanford University.

Speaking at the annual meeting of the American Association for the Advancement of Science, Field said emissions from burning fossil fuels since 2000 have largely outpaced the estimates used in a 2007 U.N. report.

The increase in greenhouse emissions is largely the result of increased burning of coal in developing countries, said Field, a member of the United Nations’ Intergovernmental Panel on Climate Change.

Earth-like planets

Earth-like planets with life-sustaining conditions are spinning around stars in our galactic neighborhood, US astrophysicists say. They just haven’t been found yet.

“There are something like a few dozen solar-type stars within something like 30 light years of the sun, and I would think that a good number of those — perhaps half of them have Earth-like planets,” Alan Boss told the annual meeting of the American Association for the Advancement of Science (AASS).

“So I think there is a very good chance that we will find some Earth-like planets within 10, 20 or 30 light years of the Sun,” the astrophysicist from the Carnegie Institution for Science told his AAAS colleagues meeting here since Thursday.

One light year equals the distance light travels in one year at the speed of 300,000 kilometers (186,000 miles) per second, or 9.46 trillion kilometers (5.88 trillion miles).

Boss is convinced that the Earth-sized planets could be found either by the Kepler space telescope US space agency NASA plans to launch on March 5, or by the French-European telescope-equipped COROT satellite that has been in orbit since 2006.

“I will be absolutely astonished if Kepler or COROT didn’t find any earth-like planets, because basically we are finding them already,” Boss told a press conference Saturday when asked why he felt so confident.

COROT has already discovered the smallest extraterrestrial planet so far. At a little over twice the Earth’s diameter, the planet is very close to its star and very hot, astronomers reported earlier this month.

Boss said Kepler and COROT will likely find so many Earth-like planets that they will “tell us how to go ahead and build the next space telescope to go and examine these planets, after we know they are there.”

The images from those new planets, he added, should identify “light from their atmosphere and tell us if they have perhaps methane and oxygen. That will be pretty strong proof they are not only habitable but actually are inhabited.”

“I am not talking about a planet with intelligence on it. I simply say if you have a habitable world … sitting there, with the right temperature with water for a billion years, something is going to come out of it.

“At least we will have microbes,” said Boss.

Raymond Jeanloz, professor of astronomy, earth and planetary science at the University of California at Berkeley, delved further into the matter.

“I can strongly reinforce Alan Boss’s point that life from this perspective that is very much driven by our understanding from the genome, is in some sense ‘inevitable,'” if the same basic building blocks of life that exist on Earth are present.

“The distinction will be more between a class of life form that can communicate with us versus … the vast abundance of life forms recorded in our fossil records, namely microbial life.”

On the possibility of finding an extra-terrestrial civilization, Boss said the research “is an interesting one and an important one to do because, even though there is a small probability of success, if you actually find something, it is an immense discovery to make.

“So you say, ‘yes, this is worth doing.'”

Hello world!

Welcome to WordPress.com. This is your first post. Edit or delete it and start blogging!