![]() ![]() "At these distances, the Milky Way's gravitational effects disturb small bodies. In the final stages of planetary formation, she explained, small bodies were expelled far from the Sun and planets, forming the spherical shell of debris and comets known as the Oort cloud. The most famous, of course, is Halley's comet, which has a retrograde orbit with an inclination of 162°, practically identical to that of 2015 BZ509," Morais said. Their orbits are typically inclined as well as retrograde. "The vast majority of retrograde objects are comets. The asteroid crosses Jupiter's path every six years, but owing to their co-orbital resonance, they never come closer than 176 million km, far enough to avoid major disturbances to the orbit of the asteroid, although Jupiter's gravity is essential to keeping the planet and Bee-Zed in a 1:1 retrograde resonance.Īll the planets and most of the asteroids in the solar system orbit the Sun in the same direction because the solar system emerged from a revolving cloud of dust and gas, most of the constituent objects of which continue to revolve as they did before. "Instead of being ejected from orbit by Jupiter, as one would expect, the asteroid is in a configuration that assures stability thanks to co-orbital resonance, meaning its motion is synchronized with the planet's, avoiding collisions," Morais said. By contrast, prograde co-orbitals that move 'with traffic' are nothing new Jupiter alone is accompanied by some 6,000 Trojan asteroids that share the giant planet's orbit.īee-Zed is unusual because it shares a planet's orbit, because its own orbit is retrograde, and above all, because it has been stable for millions of years. It is estimated that only 82 of the more than 726,000 known asteroids are orbiting the "wrong way". The confirmation that its orbit is retrograde and co-orbital with Jupiter came from these additional observations. The paper by Paul Wiegert of the University of Western Ontario, Canada, published in March in Nature, describes how object 2015 BZ509, detected in January 2015, using the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) in Hawaii, was tracked using the Large Binocular Telescope in Arizona. In partnership with Fathi Namouni at the Côte d'Azur Observatory in France, Morais developed a general theory on retrograde co-orbitals and retrograde orbital resonance. So, we're sure the asteroid is retrograde, co-orbital and stable." Now it's been confirmed after more observations that reduced the number of errors in the orbital parameters. We've known about this asteroid since 2015, but the orbit hadn't been clearly determined, and it wasn't possible to confirm the co-orbital configuration. "I was sure retrograde co-orbits existed. "It's good to have confirmation," Morais told. Morais had predicted the discovery two years earlier, so much so that the article describing observations of the asteroid published in Nature, is noted by Morais in the News & Views section of the same issue of the journal. The asteroid with the retrograde co-orbit was identified by Helena Morais, a professor at São Paulo State University's Institute of Geosciences & Exact Sciences (IGCE-UNESP). This is the same orbital period as that of Jupiter, which shares its orbit but moves in the opposite direction to the planet's motion. Asteroid 2015 BZ509, also known as Bee-Zed, takes 12 years to make one complete orbit around the Sun. In our solar system, an asteroid orbits the Sun in the opposite direction to the planets. I'm new here so correct me if I'm wrong.Image: Co-orbital bodies that orbit the Sun in the same direction as a planet can follow trajectories (blue curves with arrows) that, from the perspective of the planet, look like tadpoles, horseshoes or 'quasi-satellites'. Eg, my horse avg 30, all race avg 36, SD 2, then my horse is 3 SDs better than the rest which is very good in general terms. In terms of how to use it to benchmark, just take the difference between your horses avg and the all races avg then divide by standard deviation to find out how many standard deviations better/worse than the rest your horse is. In that case if you ran an 18 second race, it would be considered quite remarkable. However, say the SD is lower, as in there is less variance of values (eg, avg 20s, max 22s, min 18s). If you raced an 18 second race where those values were true, it wouldn't be that remarkable. So if race times were spread over a wide range of values, you would expect a high SD (eg, avg 20s, max 30s, min 10s). Standard deviation is a common way to measure how much variation there is in a set of values (in this case race times). As I understand it, it allows you to benchmark the average race times for your horse against the average for all races. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |