Sky's Up July-September 2017 - Page 22

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What advice do you have for other young people who are interested in getting into the field of astronomy ?
My advice would be to visit your local library or take classes at your school to learn more about astronomy . These may help you find local organizations on amateur astronomy . These will open up a whole new world of opportunities for you . Most importantly , you should learn something new every day . It can be something small , like familiarizing yourself with a constellation , or you can go more in depth . This will help deepen your understanding of astronomy .
What does the future hold for you as an outreach educator / astronomer ?
My ultimate goal is to become a science teacher . I plan on attending Radford University this fall and earn a degree in secondary education . I would also like to own a little science shop one day to promote science and learning in the community .
COURTESY OF Sierra Bradley Bradley runs the RVAS planetary sorting game at a STEM event at Mountain View Elementary School .

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Sky ’ s Up
7 8 9 22 Will we ever be able to study the Sun up close? Yes! NASA will launch Solar Probe Plus in 2018 and late in 2024 it will fly as close as 6 million km (less than 4 million miles) from the photosphere — the hot, bright layer of the Sun that shines on us each day. This is way inside Mercury’s orbit. It’s been a long time coming. In 1980 I was part of a group trying to convince NASA to fly a JPL mission called Solar Probe, later called Star Probe, to visit the Sun by way of Jupiter. 10 Do solar eclipses cause any problems for solar-powered satellites or the International Space Station? No, with qualifiers explained below. Any solar-powered satellites passing through the Moon’s shadow will be moving at a high speed and not experience the eclipse for very long. And most solar powered satellites carry batteries for periods when their orbits carry them into Earth’s shadow, sometimes for as long as 40 minutes. So for a healthy Earth orbiter, the eclipse is not a concern due to the loss of solar power or to the brief cooling in the Moon’s shadow. The batteries on older spacecraft eventually wear out. When that happens, a long-ish period without sunlight during orbital night might deplete the battery, leaving the satellite without power. That may permanently shut down the satellite. Again, this is unlikely to occur during an older satellite’s quick passage through the Moon’s shadow, if that were to occur. In general, a total eclipse seen from an Earth satellite would be a rare event. How are the temperatures of different parts of the Sun estimated? The sources of the estimates for temperatures in different parts of the Sun come from different areas of physics. Internal temperatures of the Sun are based on simple physics: compress a gas and it warms up. (Feel the tube of a bicycle hand pump before and after you’ve filled a tire. The tube warms up because the air compressed in it gets warmed by the compression). The Sun’s gravity compresses its gas, making the gas hotter deeper in our star. We know the strength of the Sun’s gravity because we can measure its mass. Throw in some laboratory nuclear physics and we estimate the Sun’s core has a temperature of about 17 million Celsius and a density of about 100 gram/cubic centimeter (water is 1 g/cm3 and iron is about 11 g/ cm3). When we look at the Sun’s photosphere, the layer that shines down on us every day, we can estimate its temperature using what’s called the blackbody curve. When you look at a campfire, you know from experience that the brightly glowing, yellow-orange embers are hotter than the dull red ones. Following through on this principle, we can break the Sun’s light into a spectrum (rainbow) and find out where it is brightest. That turns out to be in the green, which corresponds to a temperature of about 5700 C. Using laboratory studies of atomic physics, we can look at the various elements found emitting light in the next layer up, the chromosphere. This layer is shocking pink when seen (briefly!!) during an eclipse. The light fingerprints coming from different elements in the chromosphere tell us that its temperature is about 10,000 C near the photosphere, rising to 100,000 C near the corona. The temperature of the Sun’s upper atmosphere, the corona, was first estimated based on theoretical atomic physics with some validation coming from understanding electron-photon interactions. Later additional validation came from laboratory studies. The corona has iron ions that have lost as many as 13 electrons, requiring very high temperatures. The scattering of the photospheric spectrum by free electrons in the corona backs up estimates of the corona’s temperature being about 1 million C, and sometimes as high as 10 million C. Sky ’ s Up How does solar energy work? The Sun and other stars at the start and through the major portion of their lives generate energy by the fusion of hydrogen into helium. While there are several processes that can do this, the Sun uses perhaps the simplest, first merging two hydrogen nuclei (protons) into deuterium (proton + neutron) and then combining two deuterium nuclei to become helium (2 protons + 2 neutrons). There are other branches “burning” hydrogen to helium, and some of these branches only work in more massive stars. The energy released comes out of Einstein’s equation E = mc2. If you look up the mass of hydrogen and multiply the number by four, the product will be larger than the mass of helium: the difference is mass converted to energy. That energy takes about 700,000 years to reach the Sun’s photosphere from the core, and another 8.3 minutes to get to Earth. Here on Earth humans use solar energy in three ways. We grow plants for food, clothing, and industry, we use the Sun’s heat for warmth, and we convert sunlight into electricity. The chlorophyll in plants converts sunlight very efficiently (about 50 percent) into energy used by plants to grow their tissues. [ZH[\ۈ[YH[HZ\[]Y[[]\YZ\ܛ[[X\HHY[[[X[ZH\YY]K[Y[[ۈX\Z[Y]\\\ۈHٝ]\YY \\H]\[H\Y\XH܈][܈[ˈ][[\[Y[HX][ݚYYHH]\X]\YX[H[\HYYY]H\\Y[\\]\H[HH]\[\B]\X]\[XYH\K۝\[Y[XX]H\Y][]\HY]ܛ[[YوZ[[ۜ›وYX\Yˈ[X[]HY]YHHܛ[8&\۝\[ۈYXY[K]\\[۝\Y[XX]H X] H\[YXY[ H[H^H]XZ\XB\[H[Xۜ\\\X[\ˈH\\X[H\\H[\H[HY[[ۈH\[YH[Xۜ[[ݙH[H\H^H[YH\H[[]\H\[ [HH[XۜYH\KH[\H[K]ۈوHU‘\Y\Y\¸(ٙ\[H[^Hو[ۜ܂\ۛY\و[][˂ML]ۚX[YX܂VRH[[XYBL [HXX]XYX܂TL[[XYBLXZ]݋P\YܘZ[VRH[[XYB[XY\[YB(ۙH H0^Y\YXH (YY]ٚ[\(ۛYXHٝ\B(X\ۙHY\\T TL[YH[\[[H[ ^Y\YX\•H\Y8(\Y\ٙ\[\H[[[XY\™܈XX]XYXܜ[[š[\\\HH ŒML[KXZ]݋P\YܘZ[™H L  ML[K[]ۚX[YXܜBLM[[\\]H [K\]\X]H܈\]HXY\]Z[˂][[H\ݙ\°H M^ܙHY[YX[Y\\Y \\H[ܛX][ۈ[]]ܚ^YX[\]\]Z[XH]\X]KH8&H•\^ܙ\Y[YX\KB