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An artist’s rendering depicts a planet like the one scientists recently found to have disti

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A chart shows the first observations of night and day temperature fluctuations on a distant plane

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A UCLA scientist was part of the first team of scientists to observe distinct day and night temperatures on a planet outside our solar system, which observations experts said could help them better understand how distant planets function.

Distinct day and night temperatures on the planet upsilon Andromedae b, which is located near the constellation Andromeda, were observed by Brad Hansen, professor of astronomy and a member of UCLA’s Institute of Geophysics and Planetary Physics, and Joseph Harrington, professor of physics at the University of Central Florida.

Hansen said the observation of temperature differences on upsilon raises questions about the nature of that planet, including how similar its composition and weather systems are to Jupiter’s.

Observations like the ones his team made further scientists’ understanding of how these planets, and planets in general, work, Harrington said.

“We’ve learned more about planets that are on different stars, and that eventually informs our study of planets around our star and even the earth,” he said.

“It gives us access to more planets and the ability to now start talking about how these planets’ atmospheres function, which is essentially tied to meteorology.”

He said that though technology probably is not yet adequate to discover Earth-like planets outside our solar system, he hopes to use studies similar to the one recently conducted to better understand such planets once they are discovered.

“For planet hunters, the goal is to find something that looks like home,” Harrington said. “It’s a big challenge to find something like that, but we’ll be there to observe when those planets are discovered.”

Harrington said the observation of the distant star consisted of measuring the brightness of light emitted by the planet over time as it orbits around its star.

The planet, which rotates on its axis, orbits the star in a sinuisodal manner, meaning that the brightness of light oscillates up and down. The team was able to identify the day-night temperature fluctuation by measuring the difference between the high and low points of the brightness oscillation.

Hansen said the difference between night and day was about 2,500 degrees Fahrenheit.

Though upsilon Andromedae b is classified as a “hot Jupiter” because it is a gas giant that orbits very close to its scorching star, Hansen said the temperature fluctuations on upsilon differentiate it from its namesake.

“For gas-giant planets like Jupiter, there is a lot of wind, and this wind might take the energy from the light side and spread (temperature) evenly around the planet,” Hansen said, adding that scientists cannot observe differences between night and day temperatures on Jupiter.

The fact that scientists could observe such a difference on upsilon Andromedae b, a gas giant like Jupiter, called into question how phenomena scientists observe on planets in the solar system might differ in other parts of space.

The project, which was funded by NASA and used NASA’s Spitzer Space Telescope to make its observations, is unique because for the first time, observations were made on a planet whose orbital plane is tilted. This means scientists can still observe the planet-star system when the planet passes in front of its star.

Harrington said that because the team was only interested in comparing the light emitted over a period of time instead of measuring the star’s absolute brightness, it was able to make more accurate observations about temperature fluctuations on the planet.

“As a result, our team was a factor of 50 or 100 more accurate than the telescope was designed to be,” he said.

Hansen said roughly a 10th of one percent of the light from the total system comes from the planet instead of its star, because the planet re-emits light it absorbed from the star.

“When the planet is showing its day side to you, you’re getting slightly more luminosity (from the star-planet system),” he said. “The changes in brightness are because you have a hot side and a cold side.”

Upsilon Andromedae b, which was discovered in 1996 by a team based in Berkeley, is approximately 40 light years away from our solar system and takes about four and a half days to orbit its star.

The observations were published in the electronic version of Science Magazine on Oct. 12 and will be in the Oct. 27 print edition of Science.

Harrington, who has been studying planetary science for 20 years, said the analysis of the data took a few months, but the equipment for the analysis took roughly a year to develop.