Podcaster: Richard Drumm
Title: Space Scoop: Meet the Space Telescope Remapping Our Night Sky

Organization:365 Days Of Astronomy

Link : astrosphere.org ; http://unawe.org/kids/unawe1620/

Description: Space scoop, news for children

Bio: Richard Drumm is President of the Charlottesville Astronomical Society and President of 3D – Drumm Digital Design, a video production company with clients such as Kodak, Xerox and GlaxoSmithKline Pharmaceuticals. He was an observer with the UVa Parallax Program at McCormick Observatory in 1981 & 1982. He has found that his greatest passion in life is public outreach astronomy and he pursues it at every opportunity.

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Transcript:
This is 365 Days of Astronomy. Today we bring you a new episode in our Space Scoop series. This show is produced in collaboration with Universe Awareness, a program that strives to inspire every child with our wonderful cosmos.

Today’s story is: Meet the Space Telescope Remapping Our Night Sky

We live in one of the arms of a gigantic spiral galaxy called the Milky Way. A galaxy is a huge collection of stars, bound together by gravity. The Milky Way is so big that it takes light roughly 100,000 years to cross from one side to the other.

Due to its immense size, we currently don’t have the means to travel beyond the Milky Way. Heck, we can’t even travel to the nearest star! This means we must study it from the inside looking out!

If you’ve ever been in a hedge maze or a corn maze, you might understand why this is difficult, and why there are still so many unanswered questions about our cosmic home.

Questions like these:
– Exactly how big is the Milky Way?
– How old is it?
– How much mass does it have?
– When did it form?
– What shape is it?
– Where are the stars? And,
– How fast do they move?

Soon, these questions will be answered for the first time by a new satellite called Gaia, which is taking the best survey pictures of the Milky Way anyone’s ever seen!

Gaia is a satellite, which was launched into orbit around the Sun in December 2013 by the ESA, the European Space Agency. Using a one billion pixel digital camera, Gaia has been measuring the distance to stars and is creating the most detailed 3-dimensional map of our Galaxy yet!

For any cosmic object, you need to know its exact distance to tell its size and brightness, and everything else about it.
Astronomers believe there are roughly 100 billion stars in the Milky Way. And until today we only knew precise distances to a few hundred of these.

In the early 1980s I was one of the people who helped us find these distances. I was an observer with the University of Virginia’s Parallax Program.

The rest of the team & I took photographs of those closest few hundred stars with the 26″ Clark Refractor at McCormick Observatory here in Charlottesville, Virginia. We used Kodak 5×7″ glass spectroscopic photographic plates and did fine guiding by hand. It was hard work, let me tell you!

Gaia’s mission is to provide accurate distances for one billion stars, about 1% of the galaxy’s stars. Gaia measures 2 million stars an hour and the plan is to measure each target star 70 times over the mission to ascertain it’s location and sideways or “proper” motion.

On September 14th, just a week ago, the Gaia team released it’s first set of images, of the 1.1 billion stars is has observed; including around 400 million objects that have never been seen before! The picture in today’s album artwork shows Gaia’s first sky map.

The stripes and other artifacts in the image are a result of how Gaia scans the sky, and will gradually fade as more scans are made during the five-year mission.

In addition to processing the full billion-star catalogue, the scientists looked in detail at the roughly two million stars in common between Gaia’s first year of observations and the earlier Hipparcos and Tycho-2 Catalogues. Both of these earlier catalogues of stars are derived from ESA’s Hipparcos mission, which surveyed the sky from 1989 to 1993.

With the launch of that mission, the Parallax Program at UVa was shut down. Hipparcos was way more accurate and the ground-based work was immediately obsolete.

The plate vault at McCormick, however, has continued to be useful. Though it’s not as accurate, it does go back into the last century further than Hipparcos does. If you want to know where a certain star was in 1921, that’s where you look.

The historic Clark refractor is used for education and public outreach now. Lots of school kids see Saturn through it and are utterly amazed!

By combining Gaia’s data with information from these less precise catalogues, it was possible to start disentangling the effects of ‘parallax’ and ‘proper motion’ even just using the first year of observations.

Parallax is a small sideways motion in the apparent position of a star caused by Earth’s yearly revolution around the Sun and the amount of lateral displacement depends on a star’s distance from us.

Proper motion, on the other hand, is due to the physical movement of stars through the Galaxy as they rotate around the galactic center like some gigantic cosmic traffic jam.

There is so much information coming down from Gaia that the scientists on the team are asking the public for help making discoveries.

Gaia is great for finding transients, like stars that brighten and dim, but not so good at monitoring them, as Gaia is constantly on the move looking at new areas. So, the Gaia team needs to use other telescopes on the ground to do “follow-up” observations of Gaia’s discoveries.

If you’d like to get involved,visit the Gaia Alerts page at www.gaia.ac.uk/alerts

Hey, Here’s a Cool Fact
Gaia will measure the location of stars to an accuracy equal to measuring the width of a human hair at the north end of Scotland from the southern end of England!

And knowing Scotland, that’s probably a strand of extra fine red hair, too!

Thank you for listening to the 365 Days of Astronomy Podcast!

End of podcast:

365 Days of Astronomy
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