Archive for the ‘Astronomy’ Category

Was Earth’s Water Imported from Space?

October 6, 2011 Leave a comment

“The composition of the Earth-Moon system indicates that the Moon probably formed from a collision between the proto-Earth and a Mars-sized body.

That collision was incredibly violent, and left the Earth hot enough that its atmosphere would primarily consist of vaporized silicate rock.

Once it solidified, those conditions would have left the planet very dry, with our current water largely delivered by smaller bodies that have impacted the Earth since.

So far, only a single type of meteorite has been found to have hydrogen and oxygen isotopes that matched those found in the oceans.

But researchers have now checked a comet derived from the Kuiper belt, and showed that it also is a good match for the Earth’s oceans…

Now, using the ESA’s Herschel observatory, researchers have gotten a good reading on the comet 103P/Hartley 2, which orbits near Jupiter but probably got its start in the Kuiper belt, just outside the orbit of Neptune.

And it turns out that the deuterium/hydrogen ratio is nearly an exact match for that in Earth’s oceans.

That means a large population of comets have just become candidates for seeding our planet with water.”

A Cosmic Thermostat Controls Earth’s Temperature?

October 1, 2011 Leave a comment

“In recent years, the idea that the climate is driven by clouds and cosmic rays has received plenty of attention. Interest in the idea was prompted by a Danish physicist named Henrik Svensmark, who first suggested it in the late 1990s.

Using satellite data on cloud coverage, which became available with the establishment of the International Satellite Cloud Climatology Project in 1983, Svensmark found a correlation between lower troposphere cloud cover and the 11-year solar cycle.

He proposed that cosmic rays initiate the formation of aerosols in the lower atmosphere that then form condensation nuclei for cloud droplets, increasing cloud formation from water vapor. Since low-level clouds increase Earth’s albedo (the amount of incoming solar radiation that is reflected back into space), more clouds mean cooler temperatures.

Svensmark claimed that this mechanism was responsible for virtually every climatic event in Earth history, from ice ages to the Faint Young Sun paradox to Snowball Earth to our current warming trend. Needless to say, this would overturn decades of climate research.

Cosmic “rays” are actually energetic subatomic particles. The solar wind shields the Earth from many of the cosmic rays coming from elsewhere in the Milky Way, so the number of rays that reach the Earth is modulated by variations in solar activity, such as the well-known 11-year solar cycle.

Early work by Svensmark and a group at CERN (we recently covered their initial results) has indicated that charged particles like cosmic rays can cause molecules of sulfuric acid, water, or other vapors to combine and form aerosols (particles about 1 nanometer in diameter). This provides a potential link between cosmic rays and cloud formation.”

Messenger Takes Shocking “Cheesy” Photos of Mercury

September 30, 2011 Leave a comment

“The planet Mercury is dotted with holes that appear to be unlike any other landform yet seen in the solar system, new pictures show.

High-resolution photographs from NASA’s MESSENGER spacecraft revealed the shallow, rimless, irregularly shaped depressions—similar to the holes in Swiss cheese—in impact craters all over Mercury.

The features are “widespread both in latitude and longitude,” said study co-author David Blewett, of the Johns Hopkins University Applied Physics Laboratory in Maryland.

Dubbed hollows, the odd landforms can be tens of meters to a few kilometers wide, whereas the impact craters that contain them are tens of kilometers wide or bigger.

The hollows are often seen in clusters on the walls, floors, and peaks of the craters. Many hollows have smooth, flat bottoms and feature highly reflective material.

While Mercury had previously been thought of as a geologically dead planet, with few changes to its surface over the past billion years, “these [hollows] just look fresh,” Blewett added.

“I think there’s a distinct possibility that they’re active today.””

Kepler-16b: A Lonely Planet With Double Workload

September 17, 2011 Leave a comment

Kepler-16b is the only world known to be orbiting a binary star system. NASA/JPL-Caltech

“If you could stand on the surface of Kepler-16b, you’d have two shadows.

At sunset, you would see an orange star about the size of the sun and next to it a much fainter red star. As the stars slipped toward the horizon, they would change places in the sky, like partners in a square dance.

You would not need to be Luke Skywalker visiting his home planet of Tatooine in the movie “Star Wars” to watch the twin sunset.

The only science fiction in this story is how to make the 200 light-year journey to Kepler-16, a binary star system jointly sharing the Saturn-sized planet, Kepler-16b…

From a distance about as far as Venus orbits the sun, Kepler-16b circles both its parent stars in 221 days. The stars, which on average have about 21 million miles between them, fly around each other about every 41 days.

The whole system is perfectly aligned to Kepler’s viewing spot, with the bodies crossing paths so that tiny amounts of their radiating starlight regularly, repeatedly and predictably vanish and reappear as the stars and the planet fly past one another.”

Iron Sinks – Gold Floats?

September 9, 2011 Leave a comment

“Gold and platinum shouldn’t be rare on Earth—they shouldn’t be here at all. Or at least, they shouldn’t be in Earth’s crust. These elements, along with iridium and similar metals, love iron, and thus they were sucked into our planet’s molten iron core soon after Earth formed.

So where did all of the material for our fancy jewelry come from?

According to high-precision measurements of two isotopes, or atomic variants, of tungsten in 4-billion-old rocks from Greenland published online today in Nature, precious-metal-bearing meteorites struck Earth around this time, coating the planet in a veneer containing gold, platinum, and other elements long after their native counterparts had disappeared into the planet’s core.”

Pulsars In The Sky With Diamonds

August 25, 2011 Leave a comment

“Neutron stars form from the core of a collapsing star and, as the supernova dissipates, often rotate rapidly, creating a pulsar. In less than a million years, however, their strong magnetic fields act as a brake, slowing them down considerably. In some cases, however, the neutron star will have a nearby companion, and its gravity is sufficient to start stripping mass off it.

As the process continues, the neutron star will spin back up, creating what’s called a millisecond pulsar. In most cases, these companions are still around, visible as a bright star locked in an orbital embrace with a pulsar. Now, researchers have spotted one where the star is still there, but not visible—the neutron star has stripped it down to a crystaline core the size of Jupiter…

“The chemical composition, pressure and dimensions of the companion make it certain to be crystallized (i.e., diamond).”

Are Cloud Formations Connected With Cosmic Rays?

August 25, 2011 Leave a comment

The CLOUD (Cosmics Leaving OUtdoor Droplets) project at CERN is using the proton synchrotron at the LHC to investigate the controversial link between cosmic rays and cloud formation. This week Nature contains a paper on the first round of findings.

Cosmic rays are charged subatomic particles (mostly protons) that originate outside our solar system. The strength of our sun’s solar wind, which is tied to solar activity, controls how many of those particles penetrate Earth’s atmosphere. When solar activity is high, fewer cosmic rays make it in because they are deflected by the solar wind. Several researchers have claimed that changes in cosmic ray flux have a great effect on cloud formation, and thus have a large effect on global temperature, but little is understood about the details of the process.

The initial findings of the CLOUD experiment don’t contain anything earth-shattering, and don’t really address the possible effects on climate. Nevertheless, the experiment is showing some very interesting results.”