Stars are in constant relative motion, and inevitably, some will come close to the Sun. But how close? And what effect (if any) might they have? A sufficiently close encounter could perturb the orbits of comets in our Oort cloud, a primordial reservoir of billions of comets in the outer solar system extending to perhaps 0.5 pc (100 000 AU) from the Sun. Gravitational perturbations could push these comets onto orbits which send them into the inner solar system, where they could in principle collide with the Earth.

06/01/2015: Close encounters of the stellar kind

Stars are in constant relative motion, and inevitably, some will come close to the Sun. But how close? And what effect (if any) might they have? A sufficiently close encounter could perturb the orbits of comets in our Oort cloud, a primordial reservoir of billions of comets in the outer solar system extending to perhaps 0.5 pc (100 000 AU) from the Sun. Gravitational perturbations could push these comets onto orbits which send them into the inner solar system, where they could in principle collide with the Earth. [more]
Exactly one year ago, at 10:12 CET, Soyuz VS06 with Gaia on board took off from Europe's spaceport in French Guiana, ferrying ESA's billion-star surveyor into space. After an exciting year with a successful L2 orbit insertion, a challenging commissioning period and the start of routine operations, Gaia is now scanning the sky, mapping on average 40 million stars a day. On the occasion of the first launch anniversary, six members of the Data Processing and Analysis Consortium (DPAC) share their launch and commissioning memories.

19/12/2014: First Gaia launch anniversary

Exactly one year ago, at 10:12 CET, Soyuz VS06 with Gaia on board took off from Europe's spaceport in French Guiana, ferrying ESA's billion-star surveyor into space. After an exciting year with a successful L2 orbit insertion, a challenging commissioning period and the start of routine operations, Gaia is now scanning the sky, mapping on average 40 million stars a day. On the occasion of the first launch anniversary, six members of the Data Processing and Analysis Consortium (DPAC) share their launch and commissioning memories. [more]
During commissioning it was found that the sky background observed by Gaia is significantly higher than expected. In the past months this issue has been investigated by an independent team involving experts from ESA, industry and the Data Processing and Analysis Consortium (DPAC). Following these investigations, it is now clear that the straylight is caused by two sources: the Sun and bright objects in the sky, most notably the Milky Way.

17/12/2014: Status of Gaia straylight analysis and mitigation actions

During commissioning it was found that the sky background observed by Gaia is significantly higher than expected. In the past months this issue has been investigated by an independent team involving experts from ESA, industry and the Data Processing and Analysis Consortium (DPAC). Following these investigations, it is now clear that the straylight is caused by two sources: the Sun and bright objects in the sky, most notably the Milky Way. [more]
In a study to appear in The Astrophysical Journal, and published today on arXiv, it is estimated that Gaia will have discovered some 20,000 Jupiter mass exoplanets by the time it completes its survey in 2019. Former Gaia project scientist Michael Perryman teamed up with Lennart Lindegren from Lund Observatory and Princeton University astronomers Joel Hartman and Gáspár Bakos to make a revised estimate of the expected numbers.

06/11/2014: New study ups the predicted number of exoplanets discovered by Gaia

In a study to appear in The Astrophysical Journal, and published today on arXiv, it is estimated that Gaia will have discovered some 20,000 Jupiter mass exoplanets by the time it completes its survey in 2019. Former Gaia project scientist Michael Perryman teamed up with Lennart Lindegren from Lund Observatory and Princeton University astronomers Joel Hartman and Gáspár Bakos to make a revised estimate of the expected numbers. [more]
While scanning the sky to measure the positions and movements of stars in our Galaxy, Gaia has discovered its first stellar explosion in another galaxy. This powerful event, now named Gaia14aaa, took place in a distant galaxy some 500 million light-years away, and was revealed via a sudden rise in the galaxy's brightness between two Gaia observations separated by one month.

12/09/2014: Gaia discovers its first supernova

While scanning the sky to measure the positions and movements of stars in our Galaxy, Gaia has discovered its first stellar explosion in another galaxy. This powerful event, now named Gaia14aaa, took place in a distant galaxy some 500 million light-years away, and was revealed via a sudden rise in the galaxy's brightness between two Gaia observations separated by one month. [more]
 
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