Credit: NASA/JPL-Caltech/T. Pyle (SSC-Caltech)
A typical model has planets forming from collisions of material swirling around stars. But new laboratory experiments indicate the colliding bodies may be much smaller than most people have thought.
Filed under: Astronomy, Planetary Formation | 3 Comments »
Credit: Louise Kellogg, modified by James Rustad & Qing-zhu Yin/UC Davis
Earth may have given up its innermost secrets to a pair of California geochemists, who have used extensive computer simulations to piece together the earliest history of our planet's core.
This schematic of Earth’s crust and mantle shows the results of their study, which found extreme pressures would have concentrated iron’s heavier isotopes near the bottom of the mantle as it crystallized from an ocean of magma. Read more…
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Science fiction is lousy with examples of planets that orbit a system of two suns. Tatooine, in the Star Wars saga, is endowed with a pair of suns to light up the sky, as is the planet Magrathea in The Hitchhiker's Guide to the Galaxy. It would indeed be quite a spectacle to wake up to more than one Sun every day for us who have only one. This sight may entirely be possible to view around the young binary star system V4046 Sagittarii, as new images from the Smithsonian's Submillimeter Array (SMA) have confirmed the existence of a molecular cloud – which could harbor, or later produce planets - orbiting the twin stars. This is the first time that evidence of planetary formation around a binary system of stars has been uncovered.
Filed under: Extrasolar Planets, Planetary Formation | 12 Comments »
Eris, the largest dwarf planet beyond Neptune, is currently at its furthest point in its orbit from the Sun (an aphelion of nearly 100 AU). At this distance Eris doesn't receive very much sunlight and any heating of the Plutoid will be at a minimum. However, two recent observations of Eris have shown a rapid change in the surface composition of the body. Spectroscopic analysis suggests the concentration of frozen nitrogen has dramatically altered during the two years Eris had been at this furthest point from the Sun. This is very unexpected, there should be very little change in nitrogen concentration at this point in its 557 year orbit.
So what is going on with this strange Plutoid? Is there a mystery mechanism affecting the surface conditions of this frozen moon? Could there be some cryovolcanic process erupting? Or is the explanation a little more mundane?
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Filed under: Planetary Formation, Pluto, Solar System | 18 Comments »
We've all wondered at some point or another what mysteries our Solar System holds. After all, the eight planets (plus Pluto and all those other dwarf planets) orbit within a very small volume of the heliosphere (the volume of space dominated by the influence of the Sun), what's going on in the rest of the volume we call our home? As we push more robots into space, improve our observational capabilities and begin to experience space for ourselves, we learn more and more about the nature of where we come from and how the planets have evolved. But even with our advancing knowledge, we would be naive to think we have all the answers, so much still needs to be uncovered. So, from a personal point of view, what would I consider to be the greatest mysteries within our Solar System? Well, I'm going to tell you my top ten favourites of some more perplexing conundrums our Solar System has thrown at us. So, to get the ball rolling, I'll start in the middle, with the Sun. (None of the following can be explained by dark matter, in case you were wondering… actually it might, but only a little…)
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Filed under: Astronomy, Cosmology, Physics, Planetary Formation, Solar Astronomy, Space Flight | 46 Comments »
This protoplanetary disk in the Orion Nebula has a mass more than one hundredth that of the sun, the minimum needed to form a Jupiter-sized planet. Image credit: Bally et al 2000/Hubble Space Telescope & Eisner et al 2008/CARMA, SMA)
The Orion Nebula shines brilliantly, as it is packed with over 1,000 young stars in a region just a few light-years wide. With all those stars, there's probably the potential for thousands of planets to one day form from the dust and gas surrounding these stars, right? Actually, according to a new study, fewer than 10 percent of stars in the Orion Nebula have enough surrounding dust to make a planet the size of Jupiter. And that doesn't bode well for the planet-forming abilities of most stars, at least in forming planets the size of Jupiter or larger. "We think that most stars in the galaxy are formed in dense, Orion-like regions, so this implies that systems like ours may be the exception rather than the rule," said Joshua Eisner lead author of the study from the University of California Berkeley. This finding is also consistent with the results of current planet searches, which are finding that only about 6 percent of stars surveyed have planets the size of Jupiter or larger.
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Filed under: Planetary Formation | 9 Comments »
How planets form is one of the major questions in astronomy. Only recently have we been able to study the disks of dust and gas surrounding other stars in an effort to understand the process of how planets coalesce and form from these "protoplanetary" materials. But this is a difficult task at best, given the observational distances. "This is a vast topic with many challenges," said David Wilner from the Harvard-Smithsonian Center for Astronomy at his talk at the American Astronomical Society meeting this week. "But over the course of the past few decades with observations of nearby star systems, we've come to a basic outline of the process of solar system formation."
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Filed under: Observatories, Planetary Formation | 11 Comments »
For every backyard astronomer, we know 4.5 billion years ago, both Venus and Earth were formed with nearly the same radius, mass, density and chemical composition. Venus is like Earth's evil twin, but why is the climate on both worlds so widely varied? Scientists analysing the data from the orbiting European Venus Express spacecraft are finally putting the pieces of the geological and climatological puzzle together as they take a closer look at Venusian evolution. Read more…
Filed under: Planet News, Planetary Formation, Venus | 16 Comments »
Organic molecules are thought by scientists to be instrumental in kickstarting life as we know it on Earth. Within our Solar System they can be found in comets, and they cause the redness of the clouds of Saturn's moon Titan. New observations of a planet-forming disk around a star 220 light-years from Earth reveal for the first time that these molecules exist elsewhere in the Universe.
Astronomers at the Carnegie Institute have detected the presence of organic molecules in the dusty disk surrounding HR 4796A, an eight-million year-old star in the constellation Centaurus. Using Hubble's Near-Infrared Multi-Object Spectrometer they analyzed the light coming from the disk and found that its red color is due to large organic carbon molecules called tholins. The analysis ruled out other causes of the red light, such as iron oxide.
Filed under: Astrobiology, Planetary Formation | 11 Comments »
If Mars ever had water flowing on its surface, as the many canyons and riverbed-like features on the Red Planet seem to indicate, it also would have needed a thicker atmosphere than what encircles that planet today. New research has revealed that Mars did indeed have a thick atmosphere for about 100 million years after the planet was formed. But the only thing flowing on Mars’ surface at that time was an ocean of molten rock.
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Astronomers believe the Earth formed out of a ring of gas and dust surrounding the Sun. Over the course of several million years, dust particles stuck together, and then collided with larger and larger chunks until all the material in the ring formed up into a single planet. The heavier elements separated from the lighter elements, and sunk down into the centre of the Earth. And if astronomers are right, it's happening all over again, in a star system 424 light-years away; another Earth is under construction.
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Filed under: Planetary Formation | 2 Comments »
Even though our Solar System's gas giants vary widely in size and mass, they do have something in common. Each planet is roughly 10,000 times more massive than the combined mass of all their moons. During planetary formation, rocky moons grew out of the solid material surrounding each planet. As these moons grew larger, leftover gas slowed them down, and they fell into the planet to be consumed. The moons we see today were the last ones to form around their parent planets, after the gas had dissipated.
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Filed under: Jupiter, Planetary Formation, Saturn | 1 Comment »
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