Earth's unusual orbit through hot and cold conditions tests the limits of tolerability for any known lifeforms.

"In about 1604, Johannes Kepler fitted an ellipse model of Mars' orbit to observations of Mars," Bloomer told Space.com. "He came up with the first law of planetary motion that states that planets ...

The eight major planets in our Solar System orbit the sun on the same flat plane but at vastly different speeds. Mercury, being the closest to the sun, completes an orbit in only 88 days ...

While this model works well for large, hot planets, it falls short when applied ... Their wide, circular orbit also implies a formation scenario that preserved substantial angular momentum.

The planet, known as HD 20794d, gets farther out from its star than Mars is from the sun and, on the other end of its orbit, as close as Venus. Each orbit the planet begins out beyond the habitable ...

The climate on such a world must be beyond bizarre. A super-Earth planet that dips in and out of its star's habitable zone has been discovered just 19.7 light-years away. The planet, known as HD ...

The planet, known as HD 20794d, gets farther out from its star than Mars is from the sun and, on the other end of its orbit, as close as Venus. Each orbit the planet begins out beyond the ...