Podcaster: Richard Drumm
Title: Space Scoop: Cosmic Easter Egg
Organization:365 Days Of Astronomy
Link : astrosphere.org ; http://unawe.org/kids/unawe1711/
Description: Space scoop, news for children
Our understanding of Saturn’s rings is still evolving. A team of researchers using observations made in 2008 have managed to measure the brightness and temperature of Saturn’s rings in more detail than ever. More detail in mid-infrared images from the ground, that is.
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This week’s code is GcNqmd . Enter it into the website to unlock the achievement and enter the contest.
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 the 365 Days of Astronomy Podcast. 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.
Cosmic Easter Egg
Many ancient tribes believed that the Earth was enclosed inside a giant dome, across which the stars and planets travel each night.
Over time, we came to realize that the stars are actually very far away, scattered throughout the Milky Way Galaxy and beyond. They weren’t pinholes in a vast, dark dome, as it might appear at first glance.
However, this ancient idea is still useful. Today we call the dome the celestial sphere, and it gives us a simple way of making maps of the Universe.
Just as there are lines of longitude and latitude on Earth maps, there are lines of Right Ascension and Declination on sky maps. These coordinates help us find things in the night sky. In a very basic way, they help us organize our thinking about the Universe.
In making an astronomical map we ignore how far away the stars are. Instead, we imagine that everything we see in the sky is set on the inside of a huge ball that surrounds the Earth, just like ancient people did.
And just like Earth maps on flat paper have certain distortions in them, star charts can have distortions as well. We astronomers use flat, rectangular, paper maps from time to time, but they usually only cover a small part of the sky.
When we have flat paper maps of the whole Earth things get weird. Greenland and Antarctica get made to look rather huge. Or they get sliced up into pieces or something.
Often with maps of the whole sky, the graphic is shown as an oval or elliptical shape. The distortions are there, to be sure, but the map is kept somewhat simple.
There’s a link in the show notes that’ll take you to an image of an oval picture, that might look like a beautifully decorated Easter egg, but it represents the entire sky. This picture is actually a map that shows the tracks that the ESA’s Gaia satellite followed as it scanned the sky during its first 14 months at work.
From the ESA’s Gaia website:
“Gaia is an ambitious mission to chart a three-dimensional map of our Galaxy, the Milky Way, in the process revealing the composition, formation and evolution of the Galaxy.
Gaia will provide unprecedented positional and radial velocity measurements with the accuracies needed to produce a stereoscopic and kinematic census of about one billion stars in our Galaxy and throughout the Local Group.
This amounts to about 1% of the Galactic stellar population.
Gaia will monitor each of its target stars about 70 times over a five year period. It will precisely chart their positions, distances, movements, and changes in brightness.
It is expected to discover hundreds of thousands of new celestial objects, such as extrasolar planets and brown dwarfs, and observe hundreds of thousands of asteroids within our own Solar System.
The mission will also study about 500,000 distant quasars and will provide stringent new tests of Albert Einstein’s General Theory of Relativity.”
To achieve its mission and map the entire Milky Way Galaxy, Gaia spins slowly in space, sweeping its two telescopes across the entire sky in giant circles. The telescopes have rectangular main mirrors that are 57 x 19 inches in size, or 145 x 50 centimeters.
The spacecraft rotates very slowly, taking 6 hours to turn around once, plus it’s moving around the Sun, meaning it scans different parts of the sky every day! It sits at the Earth/Sun L2 Lagrange point, 1.5 million kilometers farther from the Sun than the Earth.
In this stable spot it orbits the Sun in the same year’s time as Earth does, but it doesn’t have Earth’s heat and its shadow messing up the observations.
The colors in that graphic tell us how often Gaia looked at different parts of the sky. The regions it scanned most often are shown in blue and the areas Gaia scanned least often are colored in peach.
Hey, Here’s A Cool Fact:
The Gaia mission got its start from the ESA Hipparcos mission which ran from 1989 to 1993. That mission measured the position of 100,000 stars. Gaia will observe 1 billion stars during its five-year mission, about 70 times each.
That means it’ll study about 40 million stars a day and it’ll have 200 times the accuracy of its predecessor mission.
Things have come a long way since the days when I was taking glass plates of a couple hundred stars with the 26″ Clark Refractor as part of the UVa Parallax Program!
Thank you for listening to the 365 Days of Astronomy Podcast!
End of podcast:
365 Days of Astronomy
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The 365 Days of Astronomy Podcast is produced by Astrosphere New Media. Audio post-production by Richard Drumm. Bandwidth donated by libsyn.com and wizzard media. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. This year we will celebrate more discoveries and stories from the universe. Join us and share your story. Until tomorrow! Goodbye!