The Diner At The Center Of The Galaxy

Deep in the heart of the spiral Milky Way galaxy, a hot vortex of matter swirls around a black hole more than a million times as massive as the sun.
Many galaxies, perhaps all, contain such a monster in the middle. These supermassive black holes sustain themselves by swallowing stars, planets, asteroids, comets and clouds of gas that wander by the crowded galactic core

Close Encounter with Enceladus

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!

Spacecraft discovers thousands of doomed comets

The ESA/NASA Solar and Heliospheric Observatory has discovered more than 3000 doomed comets that have passed close to the sun.

The Solar and Heliospheric Observatory, better known as "SOHO", is a joint project of the European Space Agency, or ESA, and NASA. Orbiting the sun at 1.5 million km, or 932,000 miles from Earth, the distant observatory has just discovered its 3000^th comet-more than any other spacecraft or astronomer. And, just about all of SOHO's comets have been destroyed.

"They just disintegrate every time we observe one," said Karl Battams, a solar scientist at the Naval Research Labs in Washington, D.C., who has been in charge of running the SOHO comet-sighting website since 2003. "SOHO sees comets that pass very close to the sun-and they just can't stand the intense sunlight."

The overwhelming majority of SOHO's comet discoveries belong to the Kreutz family. Kreutz sungrazers are fragments from the breakup of a single giant comet thousands of years ago. They get their name from 19th century German astronomer Heinrich Kreutz, who studied them in detail. On average, a new member of the Kreutz family is discovered every three days. Unfortunately for these small comets, their orbits swoop perilously close to the sun.

There's only one Kreutz comet that made it around the sun – Comet Lovejoy. And we are pretty confident it fell apart a couple of weeks afterwards

Although SOHO's comets are rapidly destroyed, they nevertheless have great scientific value. For instance, the comets' tails are buffeted and guided by the sun's magnetic fields. Watching how the tails bend and swing can tell researchers a great deal about the sun's magnetic field.

Prior to the launch of SOHO in 1995, only a dozen or so comets had ever even been discovered from space, while some 900 had been discovered from the ground since 1761. SOHO has turned the tables on these figures, making itself the greatest comet hunter of all time.

But SOHO hasn't reached this lofty perch alone. The spacecraft relies on people who sift through its data. Anyone can help because SOHO's images are freely available online in real time. Many volunteer amateur astronomers scan the data on a daily basis for signs of a new comet. The result: 95% of SOHO comets have been found by citizen scientists.

Whenever someone spots a comet, they report it to Battams. He goes over the imagery to confirm the sighting and then submits it to the Central Bureau for Astronomical Telegrams, which gives it an official name.

And the name is…you guessed it. "SOHO."

While comets spotted from the ground are named after the person who first discovered them, comets first observed by a space-based telescope are named after the spacecraft. The 3000^th comet discovered was named "SOHO-3000."

Naturally, it has already been destroyed. SOHO doesn't mind though. The Greatest Comet Hunter Ever has already moved on to the next sungrazer.

"SOHO-4000," anyone?

Cool Science on the International Space Station

NASA researchers are creating a spot colder than the vacuum of space inside the International Space Station.