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Category Archives: Astronomy
Near-Earth Asteroid Size Estimate Example
Newspapers often talk about Near-Earth Objects (NEOs) that are passing "close" to the Earth. To increase the number of clicks, the articles usually include an image implying that the NEO is very close to the Earth. I find these articles a bit irritating. Continue reading
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Smallest Rocket to Put Payload Into Earth Orbit
I just read a news article about Japan launching a 3 kg satellite into orbit using a 9.7-meter-long, two-stage rocket called the SS-520 (Figure 1). The 9.7 meter length was interesting to me because I recalled an Air & Space magazine article from 1999 that stated that the smallest rocket capable of achieving Earth orbit would be "about 30 feet long." Since 9.7 meters is 31.8 feet long, it appears that Japan's SS-520 is very near the lower size limit for rocket that can put an object into Earth orbit. Continue reading
Posted in Astronomy, Space 5 Comments
Minor Planet Eccentricity versus Perihelion Chart
While searching the web for information on the outer solar system, I encountered the graph shown in Figure 1. This graph is made using eccentricity and perihelion data for ~1000 outer solar system objects. As I looked at it, I though I could generate a similar chart using data from the JPL Small Body Database Search Engine – a wonderful tool for solar system data exploration efforts. Continue reading
An Interstellar Visitor?
Astronomers are now working on determining if a recently discovered asteroid is an interstellar visitor. The first observations of this asteroid were made by a team of researchers at the University of Hawaii's Pan-STARRS 1 telescope on Haleakala in Hawaii (Figure 1). Continue reading
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Estimating Asteroid Sizes Using Excel 2D Data Table
I recently gave a seminar on how to design products using Thermoelectric Coolers (TECs). During this presentation, I showed the audience how to generate various tables and graphs using Excel data tables. I was surprised to learn that no one in the audience had ever seen an Excel data table in action. Since the middle of a seminar on TECs is probably not the best time to divert to some Excel training, I decided to prepare a simpler example the would be easier to understand on first exposure. Continue reading
Posted in Astronomy, Excel 2 Comments
Calculate Eclipse Path Width
Yesterday, a reader asked me how to compute the totality path width for the eclipse that will cross the US on 21 Aug 2017. I wrote a post on how to perform this calculation years ago. NASA has published a path width value of 114.7 km. This width will actually vary a bit as the shadow moves across the Earth because the distance change slightly between all the bodies involved. Also, the Earth and Moon are not perfectly round, which I assume. NASA has very detailed models that even include the variations due to mountains and valleys on the Moon. Continue reading
Posted in Astronomy 6 Comments
Old-School Selling of the Exploration of Mars
My youngest son has been fascinated with Elon Musk's plans for colonizing Mars. He is not that different from his old man because in my youth Wernher von Braun (Figure 1) had me captivated with his plans for human-crewed missions to Mars. As I described von Braun's plans for exploring Mars to my son, I realized the both Musk and von Braun applied similar state-of-the-art marketing approaches. Continue reading
Ion Propulsion Math
NASA has a project known as Dawn that put a space probe in orbit around the asteroids Vesta and then Ceres. CSPAN presented an excellent Dawn mission briefing given by Marc Rayman, the Mission Director and Chief Engineer. One of the most interesting aspects of the Dawn spacecraft is its use of an ion thruster to maneuver it from one destination to another. This post presents some simple math that can be used to determine some of its key performance characteristics. Continue reading
Posted in Astronomy 4 Comments
Interstellar Radio Communication Misfire
There were an interesting series of news articles recently about the detection of a possible radio signal from the star HD164595. The actual detection occurred about a year ago, but it came to the public's attention after an astronomer mentioned it in a recent presentation. Close inspection of the results indicate that the transmission was either from a Russian military satellite or electronic noise sources down on Earth. Continue reading
View of Jupiter From Satellite Metis
The arrival of the Juno spacecraft at Jupiter has motivated me to take a look a closer look at the Jovian system. I was surprised to see that we have cataloged 67 moons, sixteen of which have been discovered since 2003 and are not yet named. One moon that was new to me is called Metis (Figure 2), which is Jupiter's innermost moon. It is very tiny and resides within Jupiter's main ring. Continue reading
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