Saturn has a great many more moons than our planet – a whopping 62. A single moon, Titan, accounts for an overwhelming 96% of all the material orbiting the planet, with a group of six other smaller moons dominating the rest. The other 55 small satellites whizzing around Saturn make up the tiny remainder along with the gas giant’s famous rings.
One of the subjects of this Cassini image, Rhea, belongs to that group of dominating six. Set against a backdrop showing Saturn and its intricate system of icy rings, Rhea dominates the scene and dwarfs its tiny companion, one of the 55 small satellites known as Epimetheus.
Although they appear to be close to one another, this is a trick of perspective – this view was obtained when Cassini was some 1.2 million km from Rhea, and 1.6 million km from Epimetheus, meaning the moons themselves had a hefty separation of 400 000 km.
However, even if they were nearer to each other, Rhea would still loom large over Epimetheus: at 1528 km across and just under half the size of our own Moon, Rhea is well over 10 times the size of Epimetheus, which is a modest 113 km across.
As is traditional for the earliest discovered moons of Saturn, both are named after figures from Greek mythology: the Titan Rhea (“mother of the gods”) and Prometheus’ brother Epimetheus (“after thinker” or “hindsight”).
Image credit: NASA/JPL-Caltech/Space Science Institute, G. Ugarković
Read more about Cassini and it’s mission here. Logikblok.
Helix Nebula Hubble
The Helix Nebula, also known as The Helix, NGC 7293, is a large planetary nebula located in the constellation Aquarius.
The annual Perseid Meteor Shower is happening now! The meteors are the remnants of Comet Swift-Tuttle, and every August, like clockwork, our planet Earth cuts through the “river of rubble” left behind along the orbit of the comet. And yet, while comets are composed chiefly of frozen gas, meteors are very flimsy. They’re material that has flaked off comets and they’re similar in consistency to cigar ash; they litter up our solar system. Most are scarcely larger than pebbles or sand grains.
In the case of the Perseids, they come crashing into Earth’s atmosphere at estimated speeds as high as 37 miles per second—133,000 miles per hour. These tiny visitors from the cold, vast voids of stellar space, have been orbiting in the solar system for perhaps hundreds or even thousands of years, but cannot survive the shock of entry, and end up streaking across the sky in a brief, blazing finale lasting but a few seconds. Their kinectic energy is used up in such processes as the production of light, heat and ionization. Thus, such a tiny particle bursts into incandescence from friction, producing the shooting star effect and can be seen from more than 100-miles away. But it’s really the light energy it develops, not the particle itself that we see.
They are named the Perseid meteors because their fiery trails, if extended to a common point of intersection, would seem to originate near to the Double Star Cluster in the constellation Perseus, which on mid August evenings rises from the northeast.
Get tips on how best to view the Perseid Meteor Shower over at NASA.
Monkey Brains And Man-Suits: The Heavy-Minded Art Of Steven Russell Black
It’s like I’m looking through the sketchbook of Hannibal Lecter: wolves in men’s clothing, screaming girls, deformities, and a death’s head. All of these are beautifully rendered and shadowed, giving the images a realistic (and surrealistic) feel.
Source: Steven Russell Black
Magellanic gemstone in the southern sky [NGC 290]
Hubble has captured the most detailed image to date of the open star cluster NGC 290 in the Small Magellanic Cloud.
The image taken with the Advanced Camera for Surveys onboard the NASA/ESA Hubble Space Telescope show a myriad of stars in crystal clear detail. The brilliant open star cluster, NGC 290, is located about 200,000 light-years away and is roughly 65 light-years across.
Credit: European Space Agency & NASA
Acknowledgements: Davide De Martin (ESA/Hubble) and Edward W. Olszewski (University of Arizona, USA)