Organization:365 Days Of Astronomy
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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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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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.
Seeing the Sun in a New Light
The ALMA radio telescope array has just done something that you kids should never do yourself. It stared directly at the Sun! The bright light of the Sun would damage your eyes. It also hurts like crazy!
In the past, people have even been blinded from looking at the Sun. With a total solar eclipse coming up this summer in the USA this is on the minds of lots of parents out there.
Now, astronomers can point special solar telescopes at the Sun, but these aren’t the same type of telescope that’s in your closet, left over from Christmas or your birthday.
These special solar telescopes eliminate most of the energy from the sunlight by either letting only one color of light get through or just by letting something like one percent of one percent of all the colors of the light get through.
By getting rid of all that extra light energy the special solar telescope makes it safe to look at the Sun. Check with your local astronomy club and they’ll have one of these special scopes you can look through.
But ALMA is a radio telescope and doesn’t have real eyes, it has very sensitive and expensive radio detectors, instead.
Although the detectors could be damaged by the bright light of the Sun, technicians took care to protect them from the intense heat and bright light.
A parabolic dish makes a great solar furnace if you wanted to maximize the Sun’s heat. The 12 meter diameter dishes can generate about 130kW of power with their collecting area.
That would be great for cooking but bad for astronomy!
The first step they took was that the curved panels of the dishes were textured by a chemical etching process to diffuse the visible and near infrared light reflecting off the dishes.
When there’s a solar flare happening, a solar filter that filters IR light and radio frequencies is used to reduce the heating at the receiver’s so-called “front end”.
When the Sun is fairly quiet a “mixer detuning” technique is used to reduce the sensitivity of the receivers. This achieves the same effect by keeping the receivers from being overpowered by the strong signals from the Sun.
It makes the radio receivers a little hard of hearing. Kind of like putting in ear plugs when you’re in a noisy environment like mowing the lawn. But for radio, not sound.
Only once these protections were in place did they dare to point the ALMA dishes in the direction of the Sun.
The light we see shining from the Sun, comes from its bright surface or photosphere. ALMA doesn’t take pictures using visible light because it sees the Universe in a different type of light.
Through ALMA’s, uh, eyes, we see, instead, a hot layer of gas just above the photosphere of the Sun. This is known as the chromosphere.
It seems like the Sun has more layers than an onion and is just as hard on your eyes!
But the picture that they got is one of the coolest new observations from ALMA, showing a large sunspot. Sunspots really are cool! They’re slightly cooler patches on the Sun, that appear as dark spots. The lower temperatures are caused by strong magnetic fields.
It’s like when you place a warm can of soda in a cool mountain stream. The water carries the can’s heat away, cooling the soda.
It’s like the magnetic field sucks the heat right out of that spot on the Sun’s surface where the field lines exit the surface, cooling it down.
And since that part of the Sun is now cooler, it appears a bit darker than the rest, and we call it a sunspot.
We don’t yet know exactly how this happens, but that’s ok. We’ll find out eventually. Science works like that.
Astronomers hope that ALMA observations of the Sun will provide them with more information on how the Sun behaves. It’s very important to properly understand the Sun, after all, it’s our main source of heat and light!
Hey, Here’s A Cool Fact:
The sunspot that was photographed by ALMA on 18 December 2015 is more than twice the size of Earth!
Thank you for listening to the 365 Days of Astronomy Podcast!
End of podcast:
365 Days of Astronomy
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!