The glittering specks in this image, resembling a distant flock of flying birds, are the stars that make up the dwarf galaxy ESO 540-31. Captured in this new image from the NASA/ESA Hubble Space Telescope, the dwarf galaxy lies just over 11 million light-years from Earth, in the constellation of Cetus (The Whale). The background of this image is full of many other galaxies, all located at vast distances from us. Dwarf galaxies are the among the smaller and dimmer members of the galactic family, typically only containing around a few hundred million stars. Although this sounds like a large number, it is small when compared to spiral galaxies like our Milky Way, which are made up of hundreds of billions of stars. A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Luca Limatola.
Read more on the ESA Portal:
www.esa.int/Our_Activities/Space_Science/A_flock_of_stars
Tags: DDO 6 ESO 540-31 Hubble Space Telescope
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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.
Credit: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA/Univ. Oxford
Tags: Venus Express
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A coronal mass ejection observed by the ESA/NASA SOHO space mission on 4 January 2002 has been coloured to indicate the intensity of the matter being ejected by the Sun. White represents the greatest intensity, red/orange somewhat less, and blue the least.
An extreme-ultraviolet image of the Sun captured by SOHO’s EIT (Extreme ultraviolet Imaging Telescope) instrument is superimposed on the image. The shaded blue disc surrounding the Sun at the centre is a mask in SOHO’s LASCO instrument that blots out direct sunlight to allow study of the details in the Sun’s corona.
Credit: SOHO (ESA/NASA)/S. Hill
Tags: Coronal Mass Ejection SOHO Sun LASCO corona EIT Extreme ultraviolet Imaging Telescope
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ESA Space Science Image of the Week: Dying star offers glimpse of our Sun’s future
This is a final act of celestial beauty before the long fade into cosmic history. Invisibly buried in the centre of this colourful swirl of gas is a dying star, roughly the same mass as the Sun.
This example is known as Kohoutek 4-55. Named after its discoverer, the Czech astronomer Luboš Kohoutec, it is located 4600 light years from Earth, in the direction of the constellation Cygnus.
As a star ages, the nuclear reactions that keep it shining begin to falter. This uncertain energy generation causes the stars to pulsate in an irregular way, casting off its outer layers into space.
As the star sheds these outer gases, the super-hot core is revealed. It gives off huge quantities of ultraviolet light, and this radiation causes the gas shells to glow, creating the fragile beauty of the nebula.
Credits: NASA, ESA and the Hubble Heritage Team (STScI/AURA). Acknowledgment: R. Sahai and J. Trauger (Jet Propulsion Laboratory)
Read more here.
Tags: PN K 4-55 Sun Hubble Space Telescope Cygnus NASA ESA Space Science Planetary nebula
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This image from the NASA/ESA Hubble Space Telescope shows NGC 1175, a galaxy with an intriguing and distinctive shape.
Galaxies come in a range of shapes and sizes. Spiral galaxies are characterised by a bright core and vast, pinwheeling arms of gas, dust and stars – NGC 1175 is such a galaxy, and also hosts something known as a ‘bar’ of material that slices through its centre. Bars affect how material circulates throughout a galaxy, and look uniquely intriguing from afar.
And there’s more. When viewed edge-on, galaxies like this one have an even more peculiar morphology: their inner regions appear to be thicker in some directions than others, causing them to adopt a shape that is boxy and resembles an unshelled peanut or giant ‘X’.
NGC 1175 was observed as part of a Hubble proposal named ‘Gems of the Galaxy Zoos’, for which a number of citizen scientists voted on the galaxies they wanted Hubble to observe when the telescope had gaps of time between scheduled projects. Voting took place on the Zooniverse platform. This image comprises infrared data gathered by Hubble’s Advanced Camera for Surveys on 18 July 2019.
Despite studies implying that our very own cosmic home, the Milky Way, has an ‘X’-shaped core, it remains unclear how and when these boxy bulges formed. A recent study led by ESA research fellow Sandor Kruk used high-resolution Hubble data to explore galaxies more distant than NGC 1175. They found that these boxy bulges began forming some seven billion years ago, when the Universe was around half its current age. Their formation is related to that of galactic bars, which are thought to have formed about two billion years before the intriguingly shaped bulges began to emerge. The stars within these bars orbit the galactic centre in complex, dynamic ways, with an array of vertical motions that contribute to the galaxies’ observed central boxy morphology.
Hubble has spied a number of boxy/peanut-shaped galaxies, including the beautiful NGC 4710. Further research into these intriguing galaxies will be made possible by ESA’s upcoming Euclid mission, which will be able to survey how often these bulges crop up across a much larger number of galaxies, and by the James Webb Space Telescope (JWST), Hubble’s successor, which will be able to observe incredibly distant galaxies like these in order to better understand their history and formation. JWST is a joint project of NASA, ESA and the Canadian Space Agency.
Credits: NASA/ESA Hubble Space Telescope and William Keel (University of Alabama) and the Galaxy Zoo team; CC BY 4.0
Tags: ESA European Space Agency Space Universe Cosmos Space Science Science Space Technology Tech Technology HST Hubble Space Telescope Galaxy Supernova NASA Creative Commons NGC 1175 zooniverse