Apparent retrograde motion As Earth (blue) passes a superior planet, such as Mars (red), the superior planet will temporarily appear to reverse its motion across the sky. Retrograde motion is the apparent motion of a planet to move in a direction opposite to that of other bodies within its system, as observed from a particular vantage point. Direct motion or prograde motion is motion in the same direction as other bodies. While the terms direct and prograde are equivalent in this context, the former is the traditional term in astronomy. Prograde was first seen in an abstract of an astronomy-related professional article in 1963.[1] Etymology[edit] The term retrograde is from the Latin word retrogradus – "backward-step", the affix retro- meaning "backwards" and gradi to step or "to go". "Mercury in retrograde" is an example of the term used as a noun for retrograde motion. Apparent motion[edit] T1, T2, ..., T5 - positions of Earth P1, P2, ..., P5 - positions of a planet A1, A2, ..., A5 - projection to celestial sphere
Planetary Transits Page Transit of Mercury on 1973 Nov 10. The transit or passage of a planet across the disk of the Sun may be thought of as a special kind of eclipse. As seen from Earth, only transits of the inner planets Mercury and Venus are possible. Planetary transits are far more rare than eclipses of the Sun by the Moon. On the average, there are 13 transits of Mercury each century. At the present time, all transits of Mercury fall within several days of May 08 and November 10. To determine whether a transit of Mercury is visible from a specific geographic location, it is simply a matter of calculating the Sun's altitude and azimuth during each phase of the transit using information tabulated in the Seven Century Catalog of Mercury Transit. In 1716, Edmond Halley published a paper describing exactly how transits could be used to measure the Sun's distance, thereby establishing the absolute scale of the solar system from Kepler's third law. Maor, Eli.
NASA Confirms Discovery of the most Earth-like Planet Yet Oh, just give it a few more decades; when the shit gets deep enough down here, the species will get serious about looking elsewhere. You and I won't get to go, of course. >:-E That hasn't anything to do with balls, but with fundamental limits of feasibility. Even if we will never travel there it matters a lot to us because it contributes to completing our understanding of the universe. You can't really talk about feasibility with something like interstellar travel, because in order to do it, we are going to need new physics and we don't know what that will be yet. There are some hints of 'distance' being a bit of an illusion in quantum physics. Even with current technology it would be possible to colonise our own solar system, the key is to not rely on planets and moons etc. Never?
New 'super-Earth' found in six-planet system An international team of astronomers has discovered what they are calling a new "super-Earth," which is seven times the size of Earth and has the right conditions to support life. Called HD40307g, the new planet exists in a zone of a nearby star and is part of a six-planet system. An artist's impression shows the very large super-Earth, left, with its host star and two other planets in the system, to its right. Called HD40307g, it takes 200 days to circle its host star. Scientists had already known about the star and its other three uninhabitable planets but after using an instrument that was more sensitive to wavelengths, they were able to discover another three, including the super-Earth. A report, appearing in Astronomy and Astrophysics, said the super-Earth exists in an area that supports liquid water and is in the outermost orbit from the star. The planet orbits the star in about 200 Earth-days and now joins a growing list of 800 known planets beyond our solar system.
Strange Super-Earth Planet Has 'Plasma' Water Atmosphere - Yahoo News Canada A nearby alien planet six times the size of the Earth is covered with a water-rich atmosphere that includes a strange "plasma form" of water, scientists say. Astronomers have determined that the atmosphere of super-Earth Gliese 1214 b is likely water-rich. However, this exoplanet is no Earth twin. The high temperature and density of the planet give it an atmosphere that differs dramatically from Earth. "As the temperature and pressure are so high, water is not in a usual form (vapor, liquid, or solid), but in an ionic or plasma form at the bottom the atmosphere — namely the interior — of Gliese 1214 b," principle investigator Norio Narita of the National Astronomical Observatory of Japan told SPACE.com by email. Using two instruments on the Subaru Telescope in Mauna Kea, Hawaii, scientists studied the scattering of light from the planet. A wellspring of exotic water View gallery Artist’s rendition of the relationship between the composition of the atmosphere and transmitted col …
Puzzling Super-Dense Space Objects Could Be a New Type of Planet Mysterious dense bodies outside the Solar System could be the remnants of ice giants similar to Neptune that wandered too close to their suns, according to results presented this week at a meeting on exoplanets at the Royal Society in London. Among the most puzzling finds of NASA’s Kepler space mission to find exoplanets, which launched in 2009, are bodies too heavy for their size. In some of the rare cases in which astronomers can estimate both the mass and the size of distant planets discovered by the probe, the objects have radiuses similar to that of Earth but are denser than pure iron. No conventional theories about planet formation can account for such densities in planets of this size. Fossil worlds Grasset and his collaborators now say that the strange bodies could be the “fossil cores” of planets that were once much larger, an idea that was first proposed by researchers in 2011.
Carbon Planets Turn Earth’s Chemistry on Its Head The study of exoplanets—worlds orbiting distant stars—is still in its early days. Yet already researchers have found hundreds of worlds with no nearby analogue: giants that could steamroll Jupiter; tiny pebbles broiling under stellar furnaces; puffy oddballs with the density of peat moss. Still other exoplanets might look familiar in broad-brush, only to reveal a topsy-turvy realm where rare substances are ordinary, and vice versa. Take carbon, for instance: the key constituent of organic matter accounts for some of humankind's most precious materials, from diamonds to oil. Despite its outsize importance, carbon is uncommon—it makes up less than 0.1 percent of Earth's bulk. On other worlds, though, carbon might be as common as dirt. The planet, known as 55 Cancri e, might have a crust of graphite several hundred kilometers thick. Carbon-based worlds would owe their distinct makeup to a planet-formation process very different from our own.
Finding the next Earth Are we alone in the Universe? For years, people have been making predictions, many using the Drake equation. That involves the use of various educated guesses about the frequency of planets, how many are habitable, and so on. Until about a decade ago, most of the values in the equation remained just that, however: guesses. In the last dozen years, we've witnessed an amazing transformation in science and appear to be on the verge of several more. The result has been an incredible buzz of information—over the course of this winter, there were a series of updated estimates on the number of planets in the galaxy (answer: lots) along with various ways of slicing and dicing the numbers. Given all this information, it seems like we're on the verge of finding Earth's twin—a small, rocky, planet sitting at just the right distance from a star to play host to liquid water. Spotting exoplanets There are two main methods we've used for identifying exoplanets: radial velocity and transit.
Hawaii Night Sky Revealed in Stunning New Video A new viral time-lapse video depicts the Milky Way over Mauna Kea, Hawaii, in amazing detail, complete with telescopes and dancing laser beams. Sean Goebel, a graduate student in astronomy at the University of Hawaii at Manoa, created the new Hawaii night sky video from photographs shot on three consecutive nights in April and four nights in the summer of 2013. Time-lapse of the observatories atop Mauna Kea, Hawaii. Credit: Sean Goebel The film features the night sky progression over Mauna Kea, a 13,803-foot (4,207 meters) mountain on Hawaii's Big Island, and its many telescopes. Goebel set up his cameras on nights when the weather was clear, the moon was small and when he knew the telescopes would be running the lasers. Filming a typical scene took about five hours, using two digital SLR cameras (a Canon 5D Mk. Goebel said he made the video just for fun. "I guess people haven’t seen lasers tracking night sky before," Goebel said. Milky Way Quiz: Test Your Galaxy Smarts
Huge Solar Filament Stretches Across the Sun Want to stay on top of all the space news? Follow @universetoday on Twitter Caption: High resolution full disc hydrogen alpha composite of the Sun on August 5, 2012, comprising of 6 images for the disc and 5 images for the prominences.Credit: Paul Andrew on Flickr. The Sun wanted to let us know there was action going on in other places in the Solar System besides Mars. Caption: Credit: 11 images combined to create this view of a large filament on the Sun. Tagged as: Solar Filaments, sun
NASA finding feeds talk of a new Earth NASA has found a new planet outside Earth's solar system that is eerily similar to Earth in important aspects. Scientists say the temperature on the surface of the planet, known as Kepler-22b, is about a comfy 72 degrees (22 Celsius). Its star could almost be a twin of Earth's sun. It probably has water and land. It was found in the middle of the habitable zone, making it the best potential target for life. The discovery announced Monday was made by NASA's Kepler planet-hunting telescope. Twice before astronomers have announced planets found in that zone, but neither was as promising. With the discovery, the Kepler space telescope has now located 2,326 potential planets during its first 16 months of operation. "This is a major milestone on the road to finding Earth's twin," said Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington. © 2011 CBS Interactive Inc.