Astronomer Mark Thompson shares his passion for the ringed planet, exposing some of its most enduring mysteries.
Of all the planets in the Solar System, there are none as stunning nor intriguing as Saturn. It has been known for thousands of years, though only with the invention of the telescope was its true nature revealed.
It’s an alien world that is easy to spot with the unaided eye and even with a basic telescope, Saturn’s true beauty is there to be enjoyed. April is a great month to take a look at the planet as it lies at opposition on April 12 — meaning it is opposite to the sun in the sky so is visible all night, rising as the sun sets and setting as the sun rises.
It only takes a magnification of around 20 to 25 times for the rings to become visible, so even a small bird-spotting telescope will resolve them, but a larger telescope is needed to see the gaps in the rings or the belts around the planet.
Haunting Photos of Saturn Moons Snapped by Cassini Spacecraft
This raw image from NASA’s Cassini spacecraft was taken on March 27, 2012. The camera was pointing toward Saturn’s moon Enceladus at approximately 19,810 miles (31,881 kilometers) away.
CREDIT: NASA/JPL-Caltech/Space Science Institute
Map of the asteroid Vespa show it is worthy of being called a protoplanet
While the colors are indeed appealing, the implications of this image from NASA’s Dawn probe are pretty interesting. The colors represent different frequencies given off by minerals on the asteroid’s surface. Green, for example, may represent pyroxene, an iron-rich mineral. According to scientists, the findings mean this:
This all goes to show that Vesta is a diverse object with different cosmic ingredients and well-separated layers. This bolsters claims that Vesta is a protoplanet — an embryonic world that might have become a major planet if it weren’t trapped in the lethal asteroid belt.
Dawn will continue to study Vespa for a year before moving on to Ceres, the largest protoplanet in the asteroid belt.
For over one hundred and fifty years, scientists have captured images of celestial objects scattered across the night sky. The Pisgah Astronomical Research Institute in North Carolina is attempting to save those historical records before they vanish into a black hole.
Mystery of oldest recorded supernova solved. In 185 A.D., Chinese astronomers noted a “guest star” that mysteriously appeared in the sky and stayed for about eight months. By the 1960s, scientists had determined that the mysterious object was the first documented supernova. Later, they pinpointed the object, known as RCW 86, as a supernova remnant located about 8,000 light-years away but remained puzzled at how the star’s spherical remains were larger than expected.
Galaxy clusters back up Einstein’s theory of relativity
Testing gravity is simple: walk out of a second-floor window and see what happens. It’s a lot tougher to test Albert Einstein’s theory of gravity — the general theory of relativity — which says that the gravity of an object warps space and time around it. Although researchers have proved general relativity on the scale of the solar system, validating it on cosmic scales has been more challenging. That’s exactly what a group of astrophysicists in Denmark have now done.
The researchers, led by Radek Wojtak of the Niels Bohr Institute at the University of Copenhagen, set out to test a classic prediction of general relativity: that light will lose energy as it is escaping a gravitational field. The stronger the field, the greater the energy loss suffered by the light. As a result, photons emitted from the center of a galaxy cluster — a massive object containing thousands of galaxies — should lose more energy than photons coming from the edge of the cluster because gravity is strongest in the center. And so, light emerging from the center should become longer in wavelength than light coming from the edges, shifting toward the red end of the light spectrum. The effect is known as gravitational redshifting.
Wojtak and his colleagues knew that measuring gravitational redshifting within a single galaxy cluster would be difficult because the effect is very small and needs to be teased apart from the redshifting caused by the orbital velocity of individual galaxies within the cluster and the redshifting caused by the expansion of the universe. The researchers approached the problem by averaging data collected from 8000 galaxy clusters by the Sloan Digital Sky Survey. The hope was to detect gravitational redshift “by studying the properties of the redshift distribution of galaxies in clusters rather than by looking at redshifts of individual galaxies separately,” Wojtak explains.
Sure enough, the researchers found that the light from the clusters was redshifted in proportion to the distance from the center of the cluster, as predicted by general relativity. “We could measure small differences in the redshift of the galaxies and see that the light from galaxies in the middle of a cluster had to ‘crawl’ out through the gravitational field, while it was easier for the light from the outlying galaxies to emerge,” Wojtak says.
This is a real image taken by the robotic spacecraft Cassini of Saturn eclipsing the sun (via).
Amazing. There is a little blue dot on the left side of the image just above the bright main rings. That is Earth, approximately a billion miles away.
Not psychology related, just an incredible image. Click for high resolution to see Earth.
The Aurora Australis taken by the crew of Expedition 29 on board the International Space Station. This sequence of shots was taken September 17, 2011 from 17:22:27 to 17:45:12 GMT, on an ascending pass from south of Madagascar to just north of Australia over the Indian Ocean.
Goodness gracious, our planet is beautiful.