NASA's Cassini Spacecraft is about to make a daring plunge through one of the plumes emerging from Saturn's moon Enceladus.
Enceladus boasts an icy, ostensibly barren landscape riddled with deep canyons, dubbed tiger stripes. Underneath its icy exterior churns a global ocean, heated in part by tidal forces from Saturn and another moon, Dione, with seafloor vents expelling water at at least 194 degrees Fahrenheit. Plumes of water vapor and icy particles jettison from its surface in geyser-like spouts, hinting that there is much more to this snowy moonscape than meets the eye.
Cassini will be soaring through the jets located at the moon's south pole, only 30 miles above the surface.
Although the October 28th flyby won't be the closest we've ever been to Enceladus, it is the closest flyby over the south pole and through the plume. We'll be exploring in situ a region of the plume that Cassini has never sampled before.
So what causes these plumes, and why are they so important? Enceladus' vast, subterranean oceans may be fizzy and full of gas. When the gas and icy particles rise to the surface, they are expelled in plumes shooting from the tiger stripes. The process is similar to shaking up a bottle of soda; the gas has nowhere to go but up and out.
However, the plumes are more than just gas and water: samples show that they also contain many of the building blocks essential to Earth-like life. This lends itself to the exciting possibility that organisms similar to those that thrive in our own deep oceans near volcanic vents exuding carbon dioxide and hydrogen sulfide might exist on Eceladus. Although it is still too early to know exactly how complex potential Enceladus' lifeforms could be, scientists speculate that at the very least microbial life is a real possibility.
In the future, a different spacecraft may journey across the solar system to visit icy Enceladus. This spacecraft, unlike Cassini, could be designed to land on Enceladus' surface, near one of its tiger stripes. Such a lander would be able to take samples more directly, bypassing the plume altogether.
Ideally, it could take samples from the edge of one of the tiger stripes, speculates Spilker. This would ensure that any microbes being expelled from Enceladus' interior would be more plentiful and easier to collect.
Until then, flybys are the best we can do. And the next one should be very good indeed. Tune in on Oct. 28th!
Bright Explosion on the Moon
Astrophysics researchers who monitor the Moon for meteoroid impacts have detected the brightest explosion in the history of their program.
For the past 8 years, astronomers have been monitoring the Moon for signs of explosions caused by meteoroids hitting the lunar surface. Lunar meteor showers have turned out to be more common than anyone expected, with hundreds of detectable impacts occurring every year.
They've just seen the biggest explosion in the history of the program.
On March 17, 2013, an object about the size of a small boulder hit the lunar surface in Mare Imbrium. It exploded in a flash nearly 10 times as bright as anything we've ever seen before.
Anyone looking at the Moon at the moment of impact could have seen the explosion--no telescope required. For about one second, the impact site was glowing like a 4th magnitude star.
Ron Suggs, an analyst at the Marshall Space Flight Center, was the first to notice the impact in a digital video recorded by one of the monitoring program's 14-inch telescopes. It jumped right out at me, it was so bright, he recalls.
The 40 kg meteoroid measuring 0.3 to 0.4 meters wide hit the Moon traveling 56,000 mph. The resulting explosion1 packed as much punch as 5 tons of TNT.
The lunar impact might have been part of a much larger event.
On the night of March 17, University of Western Ontario all-sky cameras picked up an unusual number of deep-penetrating meteors right here on Earth. These fireballs were traveling along nearly identical orbits between Earth and the asteroid belt.
This means Earth and the Moon were pelted by meteoroids at about the same time.
"My working hypothesis is that the two events are related, and that this constitutes a short duration cluster of material encountered by the Earth-Moon system.
One of the goals of the lunar monitoring program is to identify new streams of space debris that pose a potential threat to the Earth-Moon system. The March 17th event seems to be a good candidate.
Controllers of Lunar Reconnaissance Orbiter have been notified of the strike. The crater could be as wide as 20 meters, which would make it an easy target for LRO the next time the spacecraft passes over the impact site. Comparing the size of the crater to the brightness of the flash would give researchers a valuable ground truth measurement to validate lunar impact models.
Unlike Earth, which has an atmosphere to protect it, the Moon is airless and exposed. Lunar meteors crash into the ground with fair frequency. Since the monitoring program began in 2005, astronomers associated with lunar impact has detected more than 300 strikes, most orders of magnitude fainter than the March 17th event. Statistically speaking, more than half of all lunar meteors come from known meteoroid streams such as the Perseids and Leonids. The rest are sporadic meteors--random bits of comet and asteroid debris of unknown parentage.
U.S. Space Exploration Policy eventually calls for extended astronaut stays on the lunar surface. Identifying the sources of lunar meteors and measuring their impact rates gives future lunar explorers an idea of what to expect. Is it safe to go on a moonwalk, or not? The middle of March might be a good time to stay inside.
We'll be keeping an eye out for signs of a repeat performance next year when the Earth-Moon system passes through the same region of space. "Meanwhile, our analysis of the March 17th event continues."
The Moon has no oxygen atmosphere, so how can something explode? Lunar meteors don't require oxygen or combustion to make themselves visible. They hit the ground with so much kinetic energy that even a pebble can make a crater several feet wide. The flash of light comes not from combustion but rather from the thermal glow of molten rock and hot vapors at the impact site.
What Lies Inside The Jupiter
For four long centuries the gas giant's vast interior has remained hidden from view. JUNO probe, launched on August 5th, changed all that.
It's really hot inside Jupiter! No one knows exactly how hot, but scientists think it could be about 43,000°F (24,000°C) near Jupiter's center, or core.
Jupiter is made up almost entirely of hydrogen and helium. On the surface of Jupiter-and on Earth-those elements are gases. However inside Jupiter, hydrogen can be a liquid, or even a kind of metal.
These changes happen because of the tremendous temperatures and pressures found at the core.
What is pressure?
Have you ever gone swimming at the deep end of a pool? Did you notice that your ears started to hurt a little bit when you were under water? The deeper you dive, the more water there is on top of you. All of that water presses on your body-and that's pressure.
The same type of pressure happens in Jupiter's core. Under low pressure, particles of hydrogen and helium, called molecules, have lots of room to bounce around. This is when hydrogen and helium are gases.
However, the weight of all this hydrogen and helium is really heavy. This weight presses down toward the planet's core, creating high pressure. The molecules run out of room to bounce around, so instead, they slow down and crowd together. This creates a liquid.
How much pressure would you find at the center of Jupiter?
Imagine if you swam to the bottom of the Pacific Ocean. You would feel more than 16,000 pounds of force pressing down on every square inch of your body. That is approximately the weight of four cars!
The pressure at the center of Jupiter is much higher. At Jupiter's core, you would feel as much as 650 million pounds of pressure pressing down on every square inch of your body. That would be like having approximately 160,000 cars stacked up in every direction all over your body!
What lies at the very center of Jupiter?
At the moment, scientists aren't 100% sure. It may be that the planet has a solid core that is bigger than Earth. But some scientists think it could be more like a thick, boiling-hot soup.
JUNO mission is designed to find answers to such remaining questions about Jupiter. The spacecraft is orbiting the giant planet, swooping in for close-up looks to get more detailed information.
Juno has already made many new discoveries about Jupiter. Scientists hope that information from Juno will help us measure Jupiter's mass and figure out whether or not the giant planet's core is solid.
Sunset Solar Eclipse
On October 23rd, 2014, the Moon will pass in front of the sun, off-center, producing a partial solar eclipse visible in most of the United States
Sunsets are always pretty. One sunset this month could be out of this world. On Thursday, Oct. 23rd, the setting sun across eastern parts of the USA will be red, beautiful and - crescent-shaped.
It's a partial solar eclipse. In other words, the New Moon is going to 'take a bite' out of the sun.
A total eclipse is when the Moon passes directly in front of the sun, completely hiding the solar disk and allowing the sun's ghostly corona to spring into view. A partial eclipse is when the Moon passes in front of the sun, off-center, with a fraction of the bright disk remaining uncovered.
The partial eclipse of Oct. 23rd will be visible from all of the United States except Hawaii and New England. Coverage ranges from 12% in Florida to nearly 70% in Alaska. Weather permitting, almost everyone in North America will be able to see the crescent.
The eclipse will be especially beautiful in eastern parts of the USA, where the Moon and sun line up at the end of the day, transforming the usual sunset into something weird and wonderful.
Observers in the Central Time zone have the best view because the eclipse is in its maximum phase at sunset. They will see a fiery crescent sinking below the horizon, dimmed to human visibility by low-hanging clouds and mist.
Warning: Don't stare. Even at maximum eclipse, a sliver of sun peeking out from behind the Moon can still cause pain and eye damage. Direct viewing should only be attempted with the aid of a safe solar filter.
During the eclipse, don't forget to look at the ground. Beneath a leafy tree, you might be surprised to find hundreds of crescent-shaped sunbeams dappling the grass. Overlapping leaves create a myriad of natural little pinhole cameras, each one casting an image of the crescent-sun onto the ground beneath the canopy. When the eclipsed sun approaches the horizon, look for the same images cast on walls or fences behind the trees.
Here's another trick: Criss-cross your fingers waffle-style and let the sun shine through the matrix of holes. You can cast crescent suns on sidewalks, driveways, friends, cats and dogs-you name it. Unlike a total eclipse, which lasts no more than a few minutes while the sun and Moon are perfectly aligned, the partial eclipse will goes on for more than an hour, plenty of time for this kind of shadow play.
A partial eclipse may not be total, but it is totally fun.
