Early Morning Bolide
Earth is constantly under attack from space invaders, but not the kind you usually see in the latest summer sci-fi flicks. For the most part, it is sand grain-sized particles of rock and ice that constitute the ~100 tons of debris that become part of our planet every day. On any given clear night, observers in dark locations will witness some of these meteoroids as they create small streaks in the sky lasting for a second or less. As Earth orbits the Sun, we pass through numerous streams of debris left behind by comets, which give rise to annual meteor showers. As these objects plow through our atmosphere at tremendous speeds (sometimes over 100,000mph), the pressure and friction create glowing bubbles of plasma about a meter in diameter along their flight path, which we see as meteors. Not all particles are that small – larger objects create brilliant streaks overhead that are known as bolides. These larger objects take longer to burn up, so they can sometimes traverse the sky from one horizon to the other.
Pictured above, a bolide is captured in the early morning hours of January 20, 2013, by Vanderbilt Dyer Observatory’s All-Sky Camera, which is mounted on top of the observatory just to the west of the Seyfert Telescope dome (left edge of the image). Simultaneously, the same bolide was captured by a similar camera at amateur astronomer Mark Manner’s Spot Observatory. Careful inspection of Dyer Observatory’s image will show that the bolide passed through the Big Dipper (just above image center) while the image from Spot Observatory shows the bolide well to the east (left) of the Big Dipper. This change in apparent location is due to the parallax effect in which two points of view will show a nearby object in different locations with respect to farther background objects. This same effect is used by astronomers to determine the distances to stars in our section of the galaxy. Parallax can also be used to determine the height of the meteor during burn-up and even its original orbit before it was unlucky enough to encounter Earth.
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Tucked up among the wooded hilltops of northern Brentwood, Vanderbilt Dyer Observatory is considered by many to be a hidden treasure of the area. Visitors to our satellite campus not only learn about some of the cutting-edge discoveries and science in astronomy but they also get a dose of nature, history, and many other things while here. Over the years, we at Dyer Observatory have made the preservation of our facility and grounds a key mission. Preservation not only entails things such as maintaining our telescopes — it also includes keeping a record of days passed. Since 1953, we have amassed a number of interesting images, pieces of equipment, and ephemera. Every day tends to bring new surprises. In continuing our tradition of public education and outreach, Stellar Finds regularly provides an image and description of the diverse paraphernalia associated with Vanderbilt Dyer Observatory and the history of astronomy at Vanderbilt University.