Organization:365 Days Of Astronomy
Description: Space scoop, news for children
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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.
How Earth’s Broken Surface Keeps Us Alive
What makes a planet “Earth-like”?
We’ve now found over 3,500 planets around distant stars.
Though a great many of them are gas giants like Jupiter & Saturn, many of them have been described as rocky and “Earth-sized.” But that doesn’t necessarily mean they’re “Earth-like” at all!
Since we can’t hop in our spaceship and travel to any exoplanets, we have to study them from here on Earth.
Astronomers with the Sloan Digital Sky Survey have made some important observations using the APOGEE spectrograph. This is the Apache Point Observatory Galactic Evolution Experiment.
It’s an infrared spectrograph on the 2.5m Sloan Foundation Telescope at Apache Point Observatory in New Mexico.
My friends at the University of Virginia Astronomy Department built that spectrograph a few years ago.
This instrument collects light in the near-infrared part of the electromagnetic spectrum.
It then spreads it out or disperses it, like happens in a prism, to reveal signatures of different elements in the atmospheres of stars.
It’s like a cosmic barcode telling us what atoms are present in the star.
Almost 200,000 stars were surveyed by APOGEE and a fraction of them are also stars which were targeted by the NASA Kepler mission. This was a mission which was designed to find potentially Earth-like planets.
The scientific paper about those observations was presented at the AAS meeting in January 2017. It focuses on 90 Kepler stars that show evidence of hosting rocky planets, and which have also been surveyed by APOGEE.
The scientists are looking at the mix of materials inside those stars, to find out what this tells them about their planets.
Differences in the make-up of these stars and their planets could have important consequences for their chances of hosting life.
The astronomers found that the stars Kepler 102 and Kepler 407 were particularly interesting. Kepler 102 is slightly less luminous than the Sun and has five known planets.
Kepler 407 is a star almost identical in mass to the Sun and hosts at least two planets, one with a mass of less than 3 Earth masses.
102 has a mix of elements much like our Sun and 407 has a lot more silicon.
To understand what a lot more silicon might mean for the planets around Kepler 407, astronomers turned to geophysicists for help. Dr. Cayman Unterborn of Arizona State University ran computer models of planet formation.
He found that one of the planets around 407 would likely be rich in the mineral garnet because of the star’s silicon content.
Garnets have silicon tetroxide in them and are semi-precious gemstones. Garnet sand is also used in making sandpaper.
So the scientists called the planet at Kepler 407 “Janet” to sort of rhyme with “garnet.” Even though Earth is about 1/4 silicon, Janet probably has much more.
The planet at Kepler 102 is nicknamed “Olive” for the mineral olivine which is olive green in color and is common here on Earth.
It’s common in the solar system too. A beautiful type of meteorite called a pallasite is so loaded with olivine crystals it looks like stained glass.
That seemingly small difference in minerals might have major consequences for planets Janet and Olive. Garnet is a stiffer mineral than olivine, so it flows more slowly.
This means that a garnet planet like Janet would be much less likely to have long-term plate tectonics.
For those of you who don’t know, Plate Tectonics is where the continents on Earth are actually separate huge slabs of the Earth’s crust that move around, even under the oceans.
These gigantic slabs are floating on top of molten rock, and our oceans float around on top of them!
It causes all kinds of natural wonders, such as earthquakes and volcanic eruptions which pour lava from deep underground onto the surface. This material actually adds oxygen to our air supply, helping us survive.
Looking at the material in stars this way could help us choose which planets to pick for future study in our search for alien life.
Hey, Here’s A Cool Fact:
Tectonic plates move about 6 inches per year. The movement can be tracked very accurately using GPS.
Plate tectonics is believed to be essential for life on Earth, because of how volcanoes and ocean ridges recycle elements between Earth’s crust and mantle. This recycling regulates the composition of our atmosphere.
It’s entirely possible that without plate tectonics life wouldn’t have gotten started here at all.
Determining the likelihood of such geological processes on other planets will help distinguish which ones are the best targets for future examination as we search for signs of life throughout the galaxy.
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!