Cassini bids Earth farewell

Nearly 870 million miles away, Cassini turned its instruments toward Earth, snapping this gorgeous photo of our planet through Saturn's rings. Nearing the end of its mission, Cassini captured this image just days before the probe began its grand finale. Low on fuel, NASA decided to set the spacecraft on a final trajectory that would eventually end with a crash into Saturn. The team chose this particular pattern to prevent Cassini from contaminating one of the Saturnian moons (one of which is believed to be potentially habitable) with microbes from Earth. On April 26, Cassini took the first of 22 dives that will end with the fateful final collision on September 15. Godspeed, Cassini.

Global dust storms

Hubble turned 27 on April 20, and to celebrate, this week's photo is one of our favorite images the space telescope has snapped of Mars to date. In 2001, Hubble took this photo of the red planet during a massive, global dust storm. Mars has a rather thin atmosphere, however, winds can reach more than 60 miles per hour, carrying small sediments miles above the surface. While the vast majority of these events last only a few days, sometimes these incredible storms can blanket the planet in a rusty haze for weeks. The 2001 global dust storm, for example, lasted more than three months, and the 16-mile high volcano, Olympus Mons, was the only surface feature seen poking through the dense cloud coverage. Just for comparisons sake, here are a pair of images showing the planet before and during this meteorological phenomenon.

The potential for extraterrestrial life

The Galileo spacecraft captured this composite image of Jupiter's moon, Europa, in the late 1990s. Researchers believe Europa is home to a global ocean of liquid water -- nearly 60 miles deep -- beneath a frozen exterior. If this turns out to be true, Europa would contain more than twice as much water as Earth. Europa's distance from Jupiter varies due to its orbital pattern causing flexing along the surface. These disproportionate gravitational tugs are responsible for creating the ridges and cracks along the surface, producing these intricate markings as regions continuously shatter and freeze. The same tidal flexing responsible for these geological features may also cause volcanic activity along the seafloor. The subsequent heat and nutrients from such hydrothermal activity could potentially support living organisms.

Devilish landscapes

The Opportunity rover snapped this image of a dust devil traversing the Martian landscape on March 31, 2016. After scaling the rather steep Knudsen Ridge, the rover peered back at its own tracks along the southern edge of Marathon Valley. While Opportunity's twin rover, Spirit, has routinely observed dust devils in the Gusev crater, these events are rather rare sights for Opportunity. The rovers on Mars as well as the Mars Reconnaissance Orbiter (MRO) have snapped glimpses of these vortexes for years and the MRO even captured a stunning glimpse of a dust devil nearly 12-miles high. NASA recently released a video of one of these events created from a series of images snapped by the Curiosity rover. You can watch this video here.

Fixing our "eyes" in the sky

Some of the most detailed images we have of our cosmos would not be possible without the Hubble Space Telescope. Since Hubble's launch and deployment in 1990, the telescope has snapped more than 1.3 million "observations." NASA has also routinely serviced the telescope to tweak faulty equipment and upgrade its overall performance.

This photo was snapped during the first servicing mission in 1993, when astronauts installed new instruments and equipment to correct a flaw in the primary mirror. Hubble weighed about 24,000 pounds when launched, and after the final servicing mission in 2009, it now orbits at a svelte 13.5 tons. The James Webb Space Telescope will replace Hubble in October 2018 -- talk about a tough act to follow.

Nearby hellscapes

The Magellan probe took this photo of the second rock from the sun, Venus, in the '90s. However, Magellan was not the first craft to attempt to unlock the planet's many mysteries. Venus is one of the most inhospitable bodies in our solar system. The atmosphere is made predominantly of carbon dioxide, with thick clouds of sulfuric acid and a surface strewn with volcanoes and vast plains of lava. Moreover, the atmospheric pressure on the planet is enough to crush a human and the surface temperature -- at nearly 900 degrees Fahrenheit -- is more than capable of melting lead.

Needless to say, designing a craft that's capable of both landing and withstanding such conditions is no easy feat. Nonetheless, in the '70s and '80s, the Soviet Union set out to do just that with the Venera missions. In 1975, Venera 9 successfully landed in operational condition, snapping the first 180-degree image of the Venusian surface. Venera 10 similarly touched down on the inhospitable planet and transmitted data back to Earth for roughly an hour. You can check out some of these stunning -- albeit grainy -- mission images here.

The end of an era

The Cassini spacecraft snapped this photo of Saturn's small shepherd moon, Pan, on March 7. The moon orbits Saturn at a distance of about 83,000 miles in a 200-mile gap -- known as the Encke Gap -- within the planet's A-ring. The probe has regularly transmitted stunning images like this back to Earth, however, after more than a decade in orbit around the gas giant, we are now approaching the end of the Cassini mission. In September, the craft will have nearly exhausted its fuel reserves. To prevent Cassini from colliding with one of Saturn's moons and potentially contaminating the surface with "hardy" Earth microbes, the craft will be sent on a controlled dive toward Saturn, where it will quickly burn up in the planet's atmosphere.

Blue skies on the red planet -- a "curious" sunset indeed

The Curiosity rover's Mastcam snapped this breathtaking Martian sunset during a "skywatching" test on April 15, 2015. This specific image was taken between dust storms, and the faint blue haze is the result of sunlight reflecting off of dust that lingers in the atmosphere. The Curiosity team often captures both twilight and sunset images to gauge how high in the atmosphere this dust extends. Curiosity's official Twitter account originally posted this image with a quote from T.S. Eliot's The Love Song of J. Alfred Prufrock: "Let us go then, you and I when the evening is spread out against the sky: Blue sunset on Mars."

Ice mountains and cryovolcanoes

The New Horizons mission gave us our first close-up look at the dwarf planet Pluto in 2015, revealing a truly bizarre world. Photographed at a distance of 11,000 miles from the surface, this picture reveals the dwarf planet in stunning detail. The relatively smooth region depicted in the right portion of the image is known as Sputnik Planum. A series of jagged mountains extending as far as 11,000-feet high dominant the left portion of the image. The Norgay Montes formation is also highlighted in the foreground.

These craggy mountains are probably composed primarily of water ice. NASA believes it has identified two potential cryovolcanoes -- volcanoes that spew a "slurry" combination of water ice, nitrogen, ammonia, and methane -- in the southern hemisphere. The spacecraft snapped this mesmerizing image just minutes into its closest approach. Talk about first impressions...

Mimas' Everest

Mimas, the smallest of Saturn's major moons, has one of the most cratered surfaces within our solar system. The most prominent of these features is the Herschel crater, named after the astronomer who discovered Mimas, William Herschel. At more than 80 miles across, the massive formation is nearly a third of the total diameter of Mimas.

Fractures on the opposite side of Herschel were potentially caused by shockwaves. In fact, it is believed that the impact event that created the crater nearly fragmented the moon. The peak at the center is nearly 3.5-miles high, making it about as tall as Mount Everest.


Depicted above is a portion of the Namib Dune, located in the Martian Bagnold Dune Field. This feature appears as a dark band on the planet's surface, and was sculpted by Martian winds. The Curiosity rover snapped this picture in 2015 as part of the first investigation of a sand dune on a planet other than Earth. While smaller dunes and similar ripples can also be found on Earth, these larger formations -- those more than 10-feet apart -- are not part of our earthly landscape.

Juno beholds a Jovian giant

This photo of Jupiter's northern latitudes was taken by the Juno spacecraft in December 2016. The image was snapped as the spacecraft was just 10,000 miles above the planet's upper atmosphere. In the top portion of the photograph, we can see an anticyclonic storm significantly smaller than Jupiter's infamous Great Red Spot. Consequently, this meteorological phenomenon is known as the Little Red Spot. This smaller storm system is roughly the size of Earth. While the Great Red Spot appears to be shrinking in size, winds inside of the Little Red Spot have rapidly increased in recent years, causing the system to darken in color.