Proba-2 partial eclipse

As the US enjoyed a total solar eclipse on 21 August 2017, ESA’s Sun-watching Proba-2 satellite captured partial eclipses from its viewpoint, 800 km above Earth. Proba-2 orbits Earth about 14.5 times per day, and thanks to the constant change in viewing angle, it can dip in and out of the Moon’s shadow several times during a solar eclipse.

This still image shows one of the first images available from today's eclipse, taken at 17:08 GMT.

The image was taken by the SWAP imager, and shows the solar disc in extreme-ultraviolet light to capture its turbulent surface and swirling corona corresponding to temperatures of about a million degrees.

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Solar eclipse seen from Space Station

ESA astronaut Paolo Nespoli took this picture during the total solar eclipse of the Sun over USA on 21 August 2017. 

From their unique vantage point 400 km above Earth’s surface, astronauts aboard the International Space Station viewed three partial eclipses as the station traversed across the path of totality on its 90 minute-long orbits around the Earth. On one of the passes, they pictured the Moon’s fuzzy shadow on the surface of our planet.

Follow Paolo Nespoli during his six-month Vita mission at paolonespoli.esa.int

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Preparing for the eclipse

ESA astronaut Paolo Nespoli showing his set-up to photograph the eclipse of the Sun on 21 August 2017 from the International Space Station. Paolo commented: "400 mm lens with solar filter installed on the camera... eclipse 2017 , bring it on!"

From their unique vantage point 400 km above Earth’s surface, astronauts aboard the International Space Station viewed three partial eclipses as the station traversed across the path of totality on its 90 minute-long orbits around the Earth. On one of the passes, they pictured the Moon’s fuzzy shadow on the surface of our planet.

Follow Paolo Nespoli during his six-month Vita mission at paolonespoli.esa.int

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The Sun, 21 August 2017

While observers in North America will enjoy views of a total solar eclipse later today as the Moon slips between Earth and the Sun, it’s business as usual for our Proba-2 and SOHO satellites.

Proba-2 is expected to capture a series of partial eclipses, while SOHO will provide context images of the Sun and its extended atmosphere, or corona. The corona can only be seen from Earth with the naked eye during an eclipse when the Moon blocks out the bright light from the Sun, but SOHO can observe it all the time using special filters and ‘occulting masks’.

An example can be seen here, which is a composite of two SOHO images and a Proba-2 image taken earlier this morning, and composed using JHelioviewer. The central image shows an extreme-ultraviolet image of the solar disc taken by Proba-2 at 05:39 GMT, while the corona and extended atmospheric features are seen by SOHO in the red image from 2–6 solar radii, and beyond in blue (SOHO can see up to about 32 solar radii) at 00:48 and 00:54 GMT, respectively. The black circular region corresponds to an occulting mask to cut out direct sunlight that would otherwise obscure the details close to the Sun – similar to the effect of the Moon in a total solar eclipse.

Near-realtime images of the Sun from SOHO are always available here, and in the days leading up to today’s total eclipse these frequent images give scientists an idea of how the corona will look during their observations. This enables them to plan specific observations of any special regions of interest, and in the context of the state of the Sun’s activity.

A team of dedicated astronomers from ESA will be studying the eclipse from the path of totality in the USA, hoping for clear skies to capture this celestial spectacular.

In addition, astronauts aboard the International Space Station, including ESA’s Paolo Nespoli, should also be able to see some aspects of the eclipse, such as a partial eclipse and the shadow of the Moon on the surface of our planet.

Follow ESA’s ground-based activities via http://cesar.esa.int and join the conversation on Twitter with #eclipse2017 and #solareclipse. We’ll keep you posted on our activities – from ground and space – via @esascience.

Remember: never look directly at the Sun, even when partially eclipsed, without proper eye protection such as special solar eclipse glasses, or you risk permanent eye damage.

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Large Space Simulator

An external view of Europe’s largest vacuum chamber, the Large Space Simulator, which subjects entire satellites to space-like conditions ahead of launch. This 15 m-high and 10 m-diameter chamber is cavernous enough to accommodate an upended double decker bus.

Satellites are lowered down through a top hatch. Once the top and side hatches are sealed, high-performance pumps create a vacuum a billion times lower than standard sea level atmosphere, held for weeks at a time during test runs.

A 121-segment mirror array reflects simulated sunlight into the chamber, at the same time as the internal walls are pumped full of –190°C liquid nitrogen, together recreating the extreme thermal conditions prevailing in orbit.

Embedded sensors and measurement devices check whether a mission’s thermal engineers have done their job well, and if the test satellite maintains an acceptable internal temperature range without buckling or other unwanted temperature-driven effects.

The simulator is an essential part of ESA’s Test Centre in the Netherlands, the largest facility of its kind in Europe, providing a complete suite of equipment for all aspects of satellite testing under a single roof.

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Large Space Simulator

An external view of Europe’s largest vacuum chamber, the Large Space Simulator, which subjects entire satellites to space-like conditions ahead of launch. This 15 m-high and 10 m-diameter chamber is cavernous enough to accommodate an upended double decker bus.

Satellites are lowered down through a top hatch. Once the top and side hatches are sealed, high-performance pumps create a vacuum a billion times lower than standard sea level atmosphere, held for weeks at a time during test runs.

A 121-segment mirror array reflects simulated sunlight into the chamber, at the same time as the internal walls are pumped full of –190°C liquid nitrogen, together recreating the extreme thermal conditions prevailing in orbit.

Embedded sensors and measurement devices check whether a mission’s thermal engineers have done their job well, and if the test satellite maintains an acceptable internal temperature range without buckling or other unwanted temperature-driven effects.

The simulator is an essential part of ESA’s Test Centre in the Netherlands, the largest facility of its kind in Europe, providing a complete suite of equipment for all aspects of satellite testing under a single roof.

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Preview of Gaia’s sky in colour

This map is a preview of Gaia’s measurements of the sky in colour.

The image includes preliminary data from 18.6 million bright stars observed by Gaia between July 2014 and May 2016, and it shows the middle value of the colours of all stars that are observed in each pixel. The colour of each star is estimated by comparing the total amount of blue and red light recorded by Gaia.

The Galactic Plane, corresponding to the most densely populated region of our Milky Way galaxy, stands out as the roughly horizontal feature across the image. The reddest regions in the map, mainly found near the Galactic Centre, correspond to dark areas in the density of stars: these are clouds of dust that obscure part of the starlight, especially at blue wavelengths, making it appear redder. It is also possible to see the two Magellanic Clouds – small satellite galaxies of our Milky Way – in the lower part of the map.

Gaia’s first full-colour all-sky map, based on data for more than 1 billion stars, will be unleashed in its highest resolution in April 2018.

Full story: Sneak peek of Gaia's sky in colour

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