all planetary science stories

Mars' water appears to have been too salty to support life

yvette — Wed, 28 May 2008 13:10:42 -0400

A new analysis of the Martian rock that gave hints of water on the Red Planet -- and, therefore, optimism about the prospect of life -- now suggests the water was more likely a thick brine, far too salty to support life as we know it.

The finding, by scientists at Harvard University and Stony Brook University, is detailed this week in the journal Science.

Sulfur dioxide may have helped maintain a warm early Mars

404132862 — Thu, 20 Dec 2007 12:56:35 -0500

Sulfur dioxide (SO2) may have played a key role in the climate and geochemistry of early Mars, geoscientists at Harvard University and the Massachusetts Institute of Technology (MIT) suggest in the Dec. 21 issue of the journal Science. Their hypothesis may resolve longstanding questions about evidence that the climate of the Red Planet was once much warmer than it is today.

Oceans are back on Mars

Mon, 09 Jul 2007 13:40:25 -0400

Since spacecraft sent back the first close-up images of Mars more than 30 years ago, some experts have insisted that oceans once existed on the now dry, cold planet. Critics have maintained for decades that such an idea is the product of unrestrained imaginations. Now, a study published in the June 14 issue of the British journal Nature reports new evidence that our neighbor in space once boasted an ocean or oceans as big, relative to planet size, as the Atlantic on Earth. "We were able to lay to rest one of the main objections to the idea that there once were oceans on Mars," says Taylor Perron, a postdoctoral fellow in Harvard's Department of Earth and Planetary Sciences.

Strange new planet baffles astronomers

70652986 — Mon, 26 Mar 2007 06:28:15 -0400

Using a network of small automated telescopes known as HAT, Smithsonian astronomers have discovered a planet unlike any other known world. This new planet, designated HAT-P-1, orbits one member of a pair of distant stars 450 light-years away in the constellation Lacerta.

"We could be looking at an entirely new class of planets," said Gaspar Bakos, a Hubble fellow at the Harvard-Smithsonian Center for Astrophysics (CfA). Bakos designed and built the HAT network and is lead author of a paper submitted to the Astrophysical Journal describing the discovery. That paper is available online at http://arxiv.org/abs/astro-ph/0609369.

With a radius about 1.38 times Jupiter's, HAT-P-1 is the largest known planet. In spite of its huge size, its mass is only half that of Jupiter.

"This planet is about one-quarter the density of water," Bakos said. "In other words, it's lighter than a giant ball of cork! Just like Saturn, it would float in a bathtub if you could find a tub big enough to hold it, but it would float almost three times higher."

HAT-P-1 revolves around its host star every 4.5 days in an orbit one-twentieth of the distance from Earth to the Sun. Once each orbit, it passes in front of its parent star, causing the star to appear fainter by about 1.5 percent for more than two hours, after which the star returns to its previous brightness.

HAT-P-1's parent star is one member of a double-star system called ADS 16402 and is visible in binoculars. The two stars are separated by about 1500 times the Earth-Sun distance. The stars are similar to the Sun but slightly younger - about 3.6 billion years old compared to the Sun's age of 4.5 billion years.

Major funding for HATnet was provided by NASA.

Tilting at ice ages

Fri, 13 Jul 2007 09:53:49 -0400

Here's a story to cool you off on a hot summer day. One of the major mysteries of ice ages may have been solved by a Harvard climatologist.

Super-Earths may be three times more common than Jupiters

70652986 — Mon, 26 Mar 2007 06:25:36 -0400

Astronomers have discovered a new "super-Earth" orbiting a red dwarf star located about 9,000 light-years away. This newfound world weighs about 13 times the mass of the Earth and is probably a mixture of rock and ice, with a diameter several times that of Earth. It orbits its star at about the distance of the asteroid belt in our solar system, 250 million miles out. Its distant location chills it to -330 degrees Fahrenheit, suggesting that although this world is similar in structure to the Earth, it is too cold for liquid water or life.

Orbiting almost as far out as Jupiter does in our solar system, this "super-Earth" likely never accumulated enough gas to grow to giant proportions. Instead, the disk of material from which it formed dissipated, starving it of the raw materials it needed to thrive.

"This is a solar system that ran out of gas," says Harvard astronomer Scott Gaudi of the Harvard-Smithsonian Center for Astrophysics (CfA), a member of the MicroFUN collaboration that spotted the planet.

The discovery was reported March 13, 2006 in a paper posted online at http://arxiv.org/abs/astro-ph/0603276 and submitted to The Astrophysical Journal Letters for publication.

Most Milky Way stars are single

70652986 — Mon, 26 Mar 2007 06:24:33 -0400

Common wisdom among astronomers holds that most star systems in the Milky Way are multiple, consisting of two or more stars in orbit around each other. Common wisdom is wrong.

A new study by Charles Lada of the Harvard-Smithsonian Center for Astrophysics (CfA) demonstrates that most star systems are made up of single stars. Since planets probably are easier to form around single stars, planets also may be more common than previously suspected.

Astronomers have long known that massive, bright stars, including stars like the sun, are most often found to be in multiple star systems. This fact led to the notion that most stars in the universe are multiples. However, more recent studies targeted at low-mass stars have found that these fainter objects rarely occur in multiple systems. Astronomers have known for some time that such low-mass stars, also known as red dwarfs or M stars, are considerably more abundant in space than high- mass stars.

By combining these two facts, Lada came to the realization that most star systems in the Galaxy are composed of solitary red dwarfs.

"By assembling these pieces of the puzzle, the picture that emerged was the complete opposite of what most astronomers have believed," said Lada.

This research has been submitted to The Astrophysical Journal Letters for publication and is available online at http://arxiv.org/ abs/astro-ph/0601375

Spitzer puts a new spin on the Helix Nebula

70652986 — Mon, 26 Mar 2007 06:24:00 -0400

Helix Nebula (NGC 7293) is a challenging stargazing target for amateur astronomers. It is one of the closest planetary nebulas - a type of nebula formed from gas ejected by a dying sunlike star. Yet it is so large and spread out in the sky that it appears very dim in a telescope eyepiece. Long-exposure photographs unveil the true beauty of this celestial wonder. A new portrait of the Helix Nebula, created by the penetrating infrared gaze of NASA's Spitzer Space Telescope, was released Jan. 9, 2006, at the 207th meeting of the American Astronomical Society.

Although named for its resemblance to a coiling spiral seen face on, the Helix Nebula has a more complex three-dimensional structure. Previous studies showed that it consists of two gaseous disks nearly perpendicular to each other. Observers on Earth view the main disk nearly face on, making it appear more ring-shaped.

In addition to its overall structure, the Helix proved to be surprisingly complex even at the smallest scale visible to Spitzer.

"Most planetary nebulas look diffuse and uniform through telescopes," explained Joseph Hora of the Harvard-Smithsonian Center for Astrophysics (CfA), who leads the team that took the image. "Because the Helix is so close, we can see more details of its fine structure. Spitzer shows that the Helix is clumpy at very small scales."

The most striking feature of the Helix, first revealed by ground- based images, is its collection of thousands of distinct blobs that resemble comets due to their compact heads and long, streaming tails. Each "cometary knot" is much larger than an actual comet, spanning about twice the size of our solar system. Each knot holds about an Earth-mass of hydrogen and other gases that were expelled from the nebula's central star thousands of years ago.

In the Spitzer image, the cometary knots show peculiar color- coding with blue-green heads and reddish tails. The bluer, more energetic radiation at the tips comes from molecular hydrogen that has been excited by ultraviolet radiation from the nebula's central star or shocked from its fast-moving stellar wind. The tails lie behind the main body of the knots and are relatively shielded. As a result, they emit redder, less energetic radiation.

Tiny "David" telescope finds "Goliath" planet

70652986 — Mon, 26 Mar 2007 05:35:14 -0400

A newfound planet detected by a small, 4-inch-diameter telescope demonstrates that we are at the cusp of a new age of planet discovery. Soon, new worlds may be located at an accelerating pace, bringing the detection of the first Earth-sized world one step closer. "This discovery demonstrates that even humble telescopes can make huge contributions to planet searches," says Guillermo Torres of the Harvard-Smithsonian Center for Astrophysics (CfA), a co-author on the study. This is the very first extrasolar planet discovery made by a dedicated survey of many thousands of relatively bright stars in large regions of the sky. It was made using the Trans-Atlantic Exoplanet Survey (TrES), a network of small, relatively inexpensive telescopes designed to look specifically for planets orbiting bright stars.

Lifeless suns dominated early universe

70652986 — Mon, 26 Mar 2007 05:34:47 -0400

The very first generation of stars were not at all like our Sun. They were white-hot, massive stars that were very short-lived. Burning for only a few million years, they collapsed and exploded as brilliant supernovae. Those very first stars began the seeding process in the universe, spreading vital elements like carbon and oxygen, which served as planetary building blocks. This picture of the early universe comes from new calculations by Harvard astronomers Volker Bromm and Abraham Loeb (Harvard-Smithsonian Center for Astrophysics). The researchers have shown that the first Sun-like stars were lonely orbs moving through a universe devoid of planets or life. "The window for life opened sometime between 500 million and 2 billion years after the Big Bang" says Loeb. "Billions of years ago, the first low-mass stars were lonely places. The reason for that youthful solitude is embedded in the history of our universe." "Life is a recent phenomenon," Loeb states unequivocally. "We know that it took many supernova explosions to make all the heavy elements we find here on Earth and in our Sun and our bodies." This research was published in the October 23, 2003, issue of the scientific journal Nature.

Suns of all ages possess comets, maybe planets

70652986 — Mon, 26 Mar 2007 05:34:54 -0400

Astronomers observed a comet puffing out huge amounts of carbon, one of the key elements for life. The comet also emitted large amounts of water vapor as the Sun's heat baked its outer surface. When combined with previous observations suggesting the presence of evaporating comets near young stars like Beta Pictoris and old stars like CW Leonis, these data show that stars of all ages vaporize comets that swing too close. Those observations also show that planetary systems like our own, complete with a collection of comets, likely are common throughout space. "Now we can draw parallels between a comet close to home and cometary activity surrounding the star Beta Pictoris, which just might have newborn planets orbiting it. If comets are not unique to our Sun, then might not the same be true for Earth-like planets?" asks astronomer Matthew Povich. In early 2003, Comet Kudo-Fujikawa zipped past the Sun at a distance half that of Mercury's orbit. Povich and John Raymond (Harvard-Smithsonian Center for Astrophysics) and colleagues studied Kudo-Fujikawa during its close passage to gather their observations and reported their results in the Dec. 12, 2003 issue of the journal Science.

Planetary survivor strategy: Outeat, outweigh, outlast!

70652986 — Mon, 26 Mar 2007 05:34:56 -0400

Astronomers Myron Lecar and Dimitar Sasselov have found that planet formation is a contest, where a growing planet must fight for survival lest it be swallowed by the star that initially nurtured it. Of the first 100 stars found to harbor planets, more than 30 stars host a Jupiter-sized world in an orbit smaller than Mercury's, whizzing around its star in a matter of days (as opposed to our solar system where Jupiter takes 12 years to orbit the Sun). Such close orbits result from a race between a nascent gas giant and a newborn star. This research is described in the Oct. 10, 2003 issue of The Astrophysical Journal Letters. "The endgame is a race between the star and its giant planet," says Sasselov. "In some systems, the planet wins and survives, but in other systems, the planet loses the race and is eaten by the star."

Earth's birth date turned back

70652986 — Mon, 26 Mar 2007 05:30:43 -0400

Radioactive elements in rocks decay in a predictable way, like the ticking of a well-made clock that can run for millions of years. The decay marks a change in character of the elements; one type of uranium, for example, decays into lead. To measure the age of meteorites, and thereby deteremine the age of Earth itself, Harvard researcher Stein Jacobsen and his colleagues used a radioactive type of hafnium, a rare heavy metal, which decays into tungsten, a more familiar gray-white metal. The ratio of this type of tungsten to a stable variety of the same metal reveals how much hafnium decayed away, or how long the clock has ticked. According to new evidence found in meteorites, our planet is 50 to 90 million years older than previously thought.

Looking for the meaning of life at the bottom of the sea

70652986 — Mon, 26 Mar 2007 05:29:39 -0400

Charles Langmuir, Harvard professor of geochemistry, loves going to sea. "It's tremendously stimulating, wonderful, exciting, and eye-opening," he says enthusiastically. "Every time I've gone since 1984, I've seen things I've never seen before. Sometimes, they're things nobody has ever seen before. Teams of people keep the work going seven days a week, 24 hours a day. Their level of output and discovery is unmatched by anything that takes place in laboratories on land. There are no committee meetings; you don't have to drive anywhere. The sunrises, sunsets, and star-filled nights are fabulous, so are the animals you see, from jellyfish to whales." Langmuir has explored volcanic ridges and rifts on the floors of four oceans.

New moons found around Neptune

70652986 — Mon, 26 Mar 2007 05:26:48 -0400

Astronomers have discovered three new moons of Neptune, boosting the number of known satellites of the gas giant to 11. These moons are the first to be discovered orbiting Neptune since the Voyager II flyby in 1989, and the first discovered from a ground-based telescope since 1949. It now appears that each member of the giant planet's irregular satellite population is the result of an ancient collision between a former moon and a passing comet or asteroid. "These collisional encounters result in the ejection of parts of the original parent moon and the production of families of satellites. Those families are exactly what we're finding," said JJ Kavelaars of the National Research Council of Canada, one of the team leaders along with Matthew Holman of the Harvard-Smithsonian Center for Astrophysics.