River Bend Astronomy Club

City skies (right) are often significantly dimmed by sky glow. Credit: Jeremy Stanley

Step out into the darkness a few hours after sunset. What do you see overhead? If you live in a relatively unpopulated part of the world, you might see the broad stripe of the Milky Way splashed against a backdrop of black sky punctuated by countless stars. If, on the other hand, you live in a teeming metropolis, what’s visible might have much more to do with where you find yourself on the planet than where we find ourselves in the galaxy.

Artificial illumination has dramatically changed the night sky across the globe. And considering that more than half of people worldwide live in urban areas—and more than one fifth live in large cities of one million or more inhabitants—light pollution obscures the stars above billions of people.

Since 2006 a project called GLOBE at Night has been quantifying light pollution using the very people it affects as measuring instruments. The project enlists citizen scientists to make naked-eye observations of a given constellation, then compare what they see with a series of star charts calibrated for different levels of light pollution. Participants submit their observations via an online form. The GLOBE at Night’s most recent campaign, for 2012, gathered nearly 17,000 observations from participants in 92 countries. (The 2013 campaign is still accepting data for a few more weeks.)

via Citizen Scientists Track Light Pollution as Humanity Loses Touch with the Night Sky | Observations, Scientific American Blog Network.

A diagram of the Kepler space telescope. Credit: NASA

NASA’s Kepler telescope has lost its ability to precisely point toward stars, putting its exoplanet search in jeopardy. One of the reaction wheels –devices which enable the spacecraft to aim in different directions without firing thrusters – has failed. This is of grave concern because last year reaction wheel #2 failed, and now #4 has failed. Kepler scientists say the spacecraft needs at least three reaction wheels to be able to point precisely enough to hunt for planets orbiting distant stars.

“We need three wheels in service to give us the pointing precision to enable us to find planets,” said Bill Borucki, Kepler principal investigator, during a press briefing today. “Without three wheels it is unclear whether we could continue to do anything on that order.”

But the Kepler team said there are still possibilities of keeping the spacecraft in working order, or perhaps even finding other opportunities for different science for Kepler, something that doesn’t require such precise pointing abilities.

via .Universe Today-Kepler Planet-Hunting Mission in Jeopardy.

Image: NASA

Saturn’s rings are such a spectacle that you can see them through even a modest telescope. Made mostly of water ice, the rings contain countless particles, large and small, that orbit the planet in a thin plane. For decades scientists have known that gravitational tugs from Saturn’s many moons imprint patterns on the rings. Now they have discovered a new ring sculptor: oscillations of the planet itself, which promise insight into the interior of the solar system’s second-largest planet.

The discovery came about because of a close inspection of Saturn’s rings. From outermost to innermost, the three main rings are named A, B and C. In 1980, when the Voyager 1 spacecraft flew past, it found grooves in each ring that resemble those on a vinyl record. The gravitational pulls of Saturn’s moons make waves, mostly in the A ring, because that’s the one closest to the moons.

In 1991, however, Paul Rosen, then at Stanford University, and his colleagues used Voyager data to discover waves in the C ring, the one nearest the planet. Although the moons accounted for some of these waves, no one knew what caused the others.

via Saturn Is Shaking Its Rings: Scientific American.