NASA Hubble Maps the Temperature and Water Vapor on an Extreme Exoplanet

A team of scientists using NASA’s Hubble Space Telescope has made the most detailed global map yet of the glow from a turbulent planet outside our solar system, revealing its secrets of air temperatures and water vapor.

Hubble observations show the exoplanet, called WASP-43b, is no place to call home. It is a world of extremes, where seething winds howl at the speed of sound from a 3,000-degree-Fahrenheit “day” side, hot enough to melt steel, to a pitch-black “night” side with plunging temperatures below 1,000 degrees Fahrenheit.

Astronomers have mapped the temperatures at different layers of the planet's atmosphere and traced the amount and distribution of water vapor. The findings have ramifications for the understanding of atmospheric dynamics and how giant planets like Jupiter are formed.

“These measurements have opened the door for a new kinds of ways to compare the properties of different types of planets,” said team leader Jacob Bean of the University of Chicago.

First discovered in 2011, WASP-43b is located 260 light-years away. The planet is too distant to be photographed, but because its orbit is observed edge-on to Earth, astronomers detected it by observing regular dips in the light of its parent star as the planet passes in front of it.

“Our observations are the first of their kind in terms of providing a two-dimensional map on the longitude and altitude of the planet’s thermal structure that can be used to constrain atmospheric circulation and dynamical models for hot exoplanets,” said team member Kevin Stevenson of the University of Chicago.

As a hot ball of predominantly hydrogen gas, there are no surface features on the planet, such as oceans or continents that can be used to track its rotation. Only the severe temperature difference between the day and night sides can be used by a remote observer to mark the passage of a day on this world.

The planet is about the same size as Jupiter, but is nearly twice as dense. The planet is so close to its orange dwarf host star that it completes an orbit in just 19 hours. The planet also is gravitationally locked so that it keeps one hemisphere facing the star, just as our moon keeps one face toward Earth.