![]() ![]() ![]() The term Jupiters is often used to describe these worlds, and the term hot Jupiters is applied to those massive planets orbiting very near their stars. The most massive planets that transit their stars are made primarily of the two lightest elements, hydrogen and helium, as are the Sun and its two largest planets, Jupiter and Saturn. More than 20 percent of stars have somewhat smaller nearby planets, with sizes of several to a few tens of Earth masses and with orbital periods of less than three months. Some of these planets seem to be distended in size as a result of heating by their stars. Almost 1 percent of stars have such giant planets in very close orbits, with orbital periods of less than one week. Imaging works best for planets orbiting those stars that are nearest to the Sun, with infrared imaging being especially sensitive to young massive planets that orbit far from their star.īetween 5 and 10 percent of stars surveyed have planets at least 100 times as massive as Earth with orbital periods of a few Earth years or less. Direct imaging can be done by using starlight reflected off the planet or thermal infrared radiation emitted by the planet. This technique is most sensitive to massive planets orbiting hundreds of millions of kilometres from their star and has also been used to discover a population of free-floating giant planets that do not orbit any star. Microlensing relies upon measurements of the gravitational bending of light (predicted by Albert Einstein’s general theory of relativity) from a more distant source by an intervening star and its planets. ![]() The first extrasolar planets to be discovered were found in 1992 around the pulsar PSR 1257+12 by using this method. When the source is a pulsar (a rotating, magnetized neutron star), current technology can detect motions in response to a planet whose mass is as small as that of Earth’s Moon, whereas only giant planets can be detected around pulsating normal stars. Pulsation timing measures the change in distance between the signal source and the telescope by using the arrival times of signals that are emitted periodically by the source. Three other techniques that have detected extrasolar planets are pulsation timing, microlensing, and direct imaging. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.Student Portal Britannica is the ultimate student resource for key school subjects like history, government, literature, and more.Demystified Videos In Demystified, Britannica has all the answers to your burning questions.This Time in History In these videos, find out what happened this month (or any month!) in history.#WTFact Videos In #WTFact Britannica shares some of the most bizarre facts we can find.Britannica Classics Check out these retro videos from Encyclopedia Britannica’s archives.Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions. ![]()
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |