Kamikaze Comets Create Dusty Fireworks Around Fomalhaut

The moon rises over Lake Superior and Duluth's Lakeside neighborhood last March. Photo: Bob King

Yesterday night my community education astronomy class and I enjoyed an evening of skywatching along Duluth’s Skyline Parkway, where one can take in the stars above the lights and homes of the city’s Lakeside neighborhood. Standing along the rim, there’s a feeling of being suspended between heaven and Earth like an astronaut in orbit. Which reminds me – Duluth has a great pass of the space station tonight across the southern sky starting at 8:57 p.m.

One student wondered where the moon was. I explained it wouldn’t be up until well after midnight. Not so for the twin GRAIL satellites named “Ebb” and “Flow”. They’ll stare at nothing but the moon 24/7  for the next few months.

The Gravity Recovery and Interior Laboratory (GRAIL) mission measures the moon’s gravitational effects on the two satellites as they orbit around the moon. Small changes in the distance between the two craft will allow scientists to create a detailed map of the moon’s gravity field. They’ll use that information to probe the structure of the moon’s interior from upper crust to inner core. The spacecraft also carry cameras that middle school kids are using to snap photos of the moon.

Using a camera aboard one of the GRAIL spacecraft, middle school students took this picture of planet Earth floating above the lunar farside. Click to enlarge. Credit: NASA/Caltech-JPL/MIT/SRS

Called MoonKAM – Moon Knowledge Acquired by Middle school students – it’s a NASA education and outreach program where participants submit requests to have either Ebb or Flow photograph a favorite moonscape or lunar scene.

Judging by the numbers, it’s wildly popular. 27,000 schools in 52 countries signed up; the first batch of more than 60 photos taken between March 15-17 were recently relayed back to Earth.

What a fantastic way for young people to delve into science. Who knows how many careers in space and astronomy might be inspired. To read more about Moon KAM and see additional images, click HERE.

News also comes today from the European Space Agency’s orbiting Herschel Telescope, which studies the sky in the light of infrared or heat energy, of comet kamikazes around the star Fomalhaut.

Fomalhaut (center) and it disk of fluffy dust imaged by the Herschel Telescope. The dust is being replenished by the comet collisions at the rate of 2000 half-mile-wide comets a day. Fomalhaut is 25 light years from Earth. Credit: ESA

Fomalhaut is a young star just a few hundred million years old (vs. the sun’s 4.6 billion) twice the sun’s size in the constellation of Pisces Austrinus the Southern Fish. Since the 1980s astronomers have known it’s surrounded by a ring of dust and orbited by at least one planet. Recent observations of the dust suggest that the amount we see is far too much to stick around without resupply. Fomalhaut’s light should have blown most it away by now unless it’s being replenished in a big way.

“The only way to overcome this contradiction is to resupply the belt through continuous collisions between larger objects in orbit around Fomalhaut,” according to the agency. The amazing thing is the rate: the equivalent of 2000 1/2-mile wide comets colliding each day into a myriad of fluffy dust particles. Don’t worry – the star won’t run out of comets anytime soon. Scientists think between 260 billion and 83 trillion comets must populate the ring to keep the dust assembly line running. WOW!

Believe it or not the sun probably had a similar belt of comets. Several trillion of them were later tossed through gravitational interactions with giant planets Jupiter and Saturn into a huge spherical cloud or reservoir called the Oort Cloud. Located nearly a light year away, the cloud is believed to be the source for many long period comets, those that take hundreds of thousands or even millions of years to orbit the sun. Watching Fomalhaut’s dusty fireworks is a vision of the early days of our own sun.

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