Gliese 436 b

Gliese 436 b's orbit is likely misaligned with its star's rotation.

Gliese 436 b then became the smallest known transiting extrasolar planet.

In addition the hot Neptune Gliese 436 b enters secondary eclipse.

Gliese 436 b is only one of three new planets recently discovered that are significantly smaller, about the size of Neptune.

Transit observations led to the determination of Gliese 436 b's exact mass and radius, both of which are very similar to Neptune.

Assuming its true mass is comparable to those of Neptune and Gliese 436 b, 14 Earth masses is theoretically the maximum size for a terrestrial planet.

It is likely close to Gliese 436 b in mass, temperature, and (with Gliese 876 d) susceptibility to solar effects such as coronal mass ejection.

The planet has the third lowest insolation of the known transiting planets (only Gliese 436 b and HD 17156 b have lower insolation).

The most notable of these are Gliese 436 b, the first transiting hot Neptune found, and HAT-P-11b, which was recently observed by the Kepler mission.

Because tidal forces would tend to circularise the orbit of the planet on short timescales, this suggested that Gliese 436 b is being perturbed by an additional planet orbiting the star.

However, for Gliese 436 b, the transits enable the determination of the inclination, as they show that the planet's orbital plane is very nearly in the line of sight (i.e. that the inclination is close to 90 degrees).

Gliese 436 b was discovered in August 2004 by R. Paul Butler and Geoffrey Marcy of the Carnegie Institute of Washington and University of California, Berkeley, respectively, using the radial velocity method.

Scientists hypothesize that Ice VII may comprise the ocean floor of Titan as well as extrasolar planets (such as Gliese 436 b and GJ 1214 b) that are largely made of water.

If a planet is sufficiently massive, the water on it may be solid even at high temperatures, because of the high pressure caused by gravity, as it was observed on exoplanets Gliese 436 b and GJ 1214 b.

This planet was the smallest transiting planet known when first discovered, with a radius about 5 times that of Earth; but is more massive than Gliese 436 b at a true mass of 26 times that of Earth.

With the aid of an unnoticed transit automatically recorded at NMSU on January 11, 2005, and observations by amateur astronomers, it has been suggested that there is a trend of increasing inclination of the orbit of Gliese 436 b, though this trend remains unconfirmed.

But nobody really knows what Gliese 436 b is like, whether it is made of rock and iron, like the Earth, or ice and snow like Neptune, nor what the dynamics of its atmosphere might be, whether, for example, water would evaporate away from the light and fall as snow on the cold side.