It was a very good year for ESA!
Stephen’s Quintet even more amazing when Herschel and Newton combine with ground based observations. Thanks ESA!
Image: ESA/XMM-Newton (X-rays); ESA/Herschel/PACS, SPIRE (infrared); SDSS (optical)
The Stephan’s Quintet of galaxies was discovered by astronomer Édouard Stephan in 1877. At the time, however, he reported the discovery of ‘new nebulae’, as the concept of other galaxies beyond our Milky Way was only formalised in the 1920s.
This image combines observations performed at three different wavelengths, with ESA’s Herschel and XMM-Newton space observatories as well as with ground-based telescopes, to reveal the different components of the five galaxies.
Stephan’s Quintet is one of the most spectacular galactic groups known, but only four galaxies from the originally discovered quintet are physically linked – the other was later discovered to be much closer to us. NGC 7320, the galaxy in the lower part the image, lies about 40 million light-years from us, rather than the 300 million light-years of the others.
One of them is the bright source above NGC 7320 in this view, two are the intertwined galaxies immediately to the right of image centre, and the fourth is the round patch towards the lower-right corner.
Later, it was discovered that an additional galaxy, hidden beyond the left edge of this image, sits at a similar distance to these four galaxies, reinstating the group as a quintet.
Check out the submissions to ESA’s 2015 International Student Contest for Lunar Exploration.
Great job by the teams and ESA!
A look inside this amazing spacecraft. Good luck ESA!
See how students can participate in ESA activities and beyond.
Once upon a time . . . What we’ve learned about 67P/Churyumov-Gerasimenko thanks to the ESA’s Rosetta mission.
More about ESA’s very successful Venus Express mission.
The polar vortex of Venus – south pole.
ESA has a nice video version located here.
Credit: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA/Univ. Oxford
This ghostly puff of smoke is actually a mass of swirling gas and cloud at Venus’ south pole, as seen by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) aboard ESA’s Venus Express spacecraft.
Venus has a very choppy and fast-moving atmosphere – although wind speeds are sluggish at the surface, they reach dizzying speeds of around 400 km/h at the altitude of the cloud tops, some 70 km above the surface. At this altitude, Venus’ atmosphere spins round some 60 times faster than the planet itself. This is very rapid; even Earth’s fastest winds move at most about 30% of our planet’s rotation speed. Quick-moving Venusian winds can complete a full lap of the planet in just four Earth days.
Polar vortices form because heated air from equatorial latitudes rises and spirals towards the poles, carried by the fast winds. As the air converges on the pole and then sinks, it creates a vortex much like that found above the plughole of a bath. In 1979, the Pioneer Venus orbiter spotted a huge hourglass-shaped depression in the clouds, some 2000 km across, at the centre of the north polar vortex. However, other than brief glimpses from the Pioneer Venus and Mariner 10 missions in the 1970s, Venus’ south pole had not been seen in detail until ESA’s Venus Express first entered orbit in April 2006.
One of Venus Express’ first discoveries, made during its very first orbit, was confirming the existence of a huge atmospheric vortex circulation at the south pole with a shape matching the one glimpsed at the north pole.
This south polar vortex is a turbulent mix of warming and cooling gases, all surrounded by a ‘collar’ of cool air. Follow-up Venus Express observations in 2007, including this image, showed that the core of the vortex changes shape on a daily basis. Just four hours after this image the vortex looked very different and a day later it had morphed into a squashed shape unrecognisable from the eye-like structure here.
A video of the vortex, made from 10 images taken over a period of five hours, can be seen here. The vortex rotates with a period of around 44 hours.
The swirling region shown in this VIRTIS image is about 60 km above the planet’s surface. Venus’ south pole is located just up and to the left of the image centre, slightly above the wispy ‘eye’ itself.
This image was obtained on 7 April 2007 at a wavelength of 5.02 micrometres. It shows thermal-infrared emission from the cloud tops; brighter regions like the ‘eye’ of the vortex are at lower altitude and therefore hotter.
ESA astronaut Alexander Gerst took 12,500 images from space during his six months on the ISS. Sit back and enjoy the timelapse videos made from combining them.
Teresa Antoja holds a PhD in Physics and works as Research Fellow on the Gaia Mission.