[Space Science]The Highligh Images in Week
ESA have released the highlight images in this week on April 14 that are Blue,Central-eastern Brazil,Gaia sky scan, Two million stars in our Galaxy.
Kilometres of blue in the white-sanded Bahamas, as seen from the International Space Station - an image shared by ESA astronaut Thomas Pesquet on social media.(Credits: ESA/NASA)
Sentinel-2A takes us over central-eastern Brazil – more specifically where the Bahia, Tocantins and Goiás states meet.
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Here we can see a large, flat plateau blanked with fields benefiting from rich soils and an apparent abundance of water, before falling off into a green, hilly valley (left). The straight lines in the image are roads, such as the highway running in a nearly straight line from the centre-top to bottom of the image.
The area is particularly known for soybean production. The country’s soybean output has increased by more than 3000% since the 1970s, and Brazil is the second largest global producer of soybeans after the US. Other crops in this area include corn, coffee and cotton.
A distinctive feature in this image is the circles – mainly at the centre. These shapes were created by a central-pivot irrigation system, where a long water pipe rotates around a well at the centre of each plot. The varying colours show different types of crop, or different stages of growth.
The two-satellite Sentinel-2 mission is designed to monitor changing lands, including crop type and health. While the first satellite has been in orbit since 2015, its Sentinel-2B twin was launched on 7 March. Together, the satellites will provide new images of Earth’s land surfaces every five days.
This image, also featured on the Earth from Space video programme, was captured by the Copernicus Sentinel-2A satellite on 8 August 2016.
(Credits: contains modified Copernicus Sentinel data (2016), processed by ESA , CC BY-SA 3.0 IGO)
Gaia sky scan
This may look like a brightly decorated Easter egg wrapping, but it actually represents how ESA’s Gaia satellite scanned the sky during its first 14 months of science operations, between July 2014 and September 2015.
The oval represents the celestial sphere, with the colours indicating how frequently the different portions of the sky were scanned. Blue represents the regions scanned most frequently in that time period; the lighter colours lesser so.
The satellite scans great circles on the sky, with each lasting about six hours. During the first month, the scanning procedure was such that the ecliptic poles were always included. This meant that Gaia observed the stars in those regions many times, providing an invaluable database for the initial calibration of the observations.
Then, the satellite started its main survey, scanning in such a way to achieve the best possible coverage of the whole sky.
These initial 14 months provided the first catalogue of the brightness and precise position of more than a billion stars, the largest all-sky survey of celestial objects to date.
Over its five-year mission, Gaia will survey one billion stars in our Galaxy and local galactic neighbourhood, measuring their position and motion at unprecedented accuracy, in order to build the most precise 3D map of the Milky Way and answer questions about its structure, origin and evolution.
(Credits: ESA/Gaia/DPAC; acknowledgement: B. Holl (University of Geneva, Switzerland) on behalf of DPAC)
Two million stars in our Galaxy
The positions of two million stars in our Galaxy, based on data from the Tycho-Gaia Astrometric Solution, one of the products of the first Gaia data release.
The stars are plotted in Galactic coordinates and using a rectangular projection: in this, the plane of the Milky Way stands out as the horizontal band with greater density of stars. The stripes visible in the early frames reflect the way Gaia scans the sky and the preliminary nature of the first data release.
The shape of the Orion constellation can be spotted towards the right edge of the frame, just below the Galactic Plane. Two stellar clusters – groups of stars that were born together and consequently move together – can be seen towards the left edge of the frame: these are the alpha Persei (Per OB3) and Pleiades open clusters.(Credits: ESA/Gaia/DPAC)