Waspie_Dwarf Posted July 22, 2014 #1 Share Posted July 22, 2014 Transiting Exoplanet with Longest Known Year Cambridge, MA - Astronomers have discovered a transiting exoplanet with the longest known year. Kepler-421b circles its star once every 704 days. In comparison, Mars orbits our Sun once every 780 days. Most of the 1,800-plus exoplanets discovered to date are much closer to their stars and have much shorter orbital periods."Finding Kepler-421b was a stroke of luck," says lead author David Kipping of the Harvard-Smithsonian Center for Astrophysics (CfA). "The farther a planet is from its star, the less likely it is to transit the star from Earth's point of view. It has to line up just right." Read more... Link to comment Share on other sites More sharing options...
shrooma Posted July 22, 2014 #2 Share Posted July 22, 2014 (edited) QUOTE- "The farther a planet is from its star, the less likely it is to transit the star from Earth's point of view. It has to line up just right." . i'd have thought it was the plane that counted, not the distance? if you're viewing it from the top down, it won't transit, but if you view it along the orbital plane, it would.... . Edited July 22, 2014 by shrooma Link to comment Share on other sites More sharing options...
Waspie_Dwarf Posted July 22, 2014 Author #3 Share Posted July 22, 2014 i'd have thought it was the plane that counted, not the distance? if you're viewing it from the top down, it won't transit, but if you view it along the orbital plane, it would.... The easiest way for me to explain this is with a diagram. In this diagram we are viewing a solar system side on (and obviously not to scale). Both planet A and planet B orbit their star with the same inclination (i.e. they orbit in the same plane). However A, being closer to the star will transit from the point of view of an observer from Earth whereas B won't. 1 Link to comment Share on other sites More sharing options...
shrooma Posted July 22, 2014 #4 Share Posted July 22, 2014 The easiest way for me to explain this is with a diagram. . ta Waspie! 1 Link to comment Share on other sites More sharing options...
Calibeliever Posted July 22, 2014 #5 Share Posted July 22, 2014 QUOTE- "The farther a planet is from its star, the less likely it is to transit the star from Earth's point of view. It has to line up just right." . i'd have thought it was the plane that counted, not the distance? if you're viewing it from the top down, it won't transit, but if you view it along the orbital plane, it would.... . I think "less likely" just means at any particular time, because it only comes around every 708 days. Link to comment Share on other sites More sharing options...
paperdyer Posted July 22, 2014 #6 Share Posted July 22, 2014 The easiest way for me to explain this is with a diagram. In this diagram we are viewing a solar system side on (and obviously not to scale). Both planet A and planet B orbit their star with the same inclination (i.e. they orbit in the same plane). However A, being closer to the star will transit from the point of view of an observer from Earth whereas B won't. But wouldn't Earth and planet A be on the same plane? Link to comment Share on other sites More sharing options...
Waspie_Dwarf Posted July 22, 2014 Author #7 Share Posted July 22, 2014 But wouldn't Earth and planet A be on the same plane? Their orbital planes are not the same. You could argue that they are in the same orbital plane ONLY when the planet is transiting the star (and half an orbit later when the planet is behind the star from Earth's pov). Look at the diagram. The line on which I have drawn planets A and B represents the orbital plane of the planets. It is inclined with respect to the Earth. When A transits the star it, the star and the Earth are all in a straight line, at other times they are not. Planet B is in the same orbital plane as planet A but, because it is further from the star it always passes above or below the star from Earth's pov. Link to comment Share on other sites More sharing options...
paperdyer Posted July 22, 2014 #8 Share Posted July 22, 2014 Their orbital planes are not the same. You could argue that they are in the same orbital plane ONLY when the planet is transiting the star (and half an orbit later when the planet is behind the star from Earth's pov). Look at the diagram. The line on which I have drawn planets A and B represents the orbital plane of the planets. It is inclined with respect to the Earth. When A transits the star it, the star and the Earth are all in a straight line, at other times they are not. Planet B is in the same orbital plane as planet A but, because it is further from the star it always passes above or below the star from Earth's pov. Thanks Waspie, what I should have said tat the two are on the same geometric plane we we can see it and only then. I didn't mean to infer Earth and plant A orbitted at the same plane realative to their suns. Link to comment Share on other sites More sharing options...
GigglyRedhead Posted July 22, 2014 #9 Share Posted July 22, 2014 Exoplanets, fascinating stuff. Link to comment Share on other sites More sharing options...
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