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STS-120 day 2 highlights

Flight Day 2 of Discovery's mission focused on heat shield inspections. This movie shows the day's highlights.


STS-120 day 1 highlights

The highlights from shuttle Discovery's launch day are packaged into this movie.


STS-118: Highlights

The STS-118 crew, including Barbara Morgan, narrates its mission highlights film and answers questions in this post-flight presentation.

 Full presentation
 Mission film

STS-120: Rollout to pad

Space shuttle Discovery rolls out of the Vehicle Assembly Building and travels to launch pad 39A for its STS-120 mission.


Dawn leaves Earth

NASA's Dawn space probe launches aboard a Delta 2-Heavy rocket from Cape Canaveral to explore two worlds in the asteroid belt.

 Full coverage

Dawn: Launch preview

These briefings preview the launch and science objectives of NASA's Dawn asteroid orbiter.

 Launch | Science

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Earth-like planets around Alpha Centauri?

Posted: March 12, 2008

Alpha Centauri, the closest star system to our Solar System, should harbour detectable Earth-like planets, according to a new study by astronomers at the University of Santa Cruz.

All-sky map showing the location of Alpha Centauri, the closest stellar system to the Sun, and one which may offer favourable conditions to terrestrial life. Image: NOAA.

Computer simulations of planet formation were performed to show that terrestrial planets are likely to have formed around one of the three stars in the system, Alpha Centauri B. Moreover, the planets would have formed in the 'habitable zone", where liquid water can exist on the planet's surface. Although many different simulations were performed, starting with a variety of different initial conditions, in every case a system of multiple planets evolved with at least one planet about the size of Earth.

The team are confident that a rocky, Earth-like planet could be detected around Alpha Centauri B using the existing Doppler detection method, which has already revealed the majority of the 228 known extrasolar planets. "If they exist, we can observe them," said Guedes, who is the first author on the paper describing the new findings. The Doppler method measures the shift in light from a star to detect the tiny wobble induced by the gravitational tug of an orbiting planet. Detecting small planets is particularly challenging because of the relatively small wobble induced in the parent star, and around five years worth of observations would be needed to detect an Earth-like planet around Alpha Centauri B. But this star offers favourable observing conditions because its position in the sky gives it a long period of observability from the Southern Hemisphere each year. An observation program using the 1.5 metre telescope at the Cerro Tololo Inter-American Observatory in Chile is planned to intensively study Alpha Centauri A and B in the hope to detect real planets similar to the ones that emerged in the computer simulations. "I think the planets are there, and it's worth a try to have a look," co-author Laughlin said.

The Planets
From tiny Mercury to distant Neptune and Pluto, The Planets profiles each of the Solar System's members in depth, featuring the latest imagery from space missions. The tallest mountains, the deepest canyons, the strongest winds, raging atmospheric storms, terrain studded with craters and vast worlds of ice are just some of the sights you'll see on this 100-page tour of the planets.

Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.

3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!


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