The Hubble Space Telescope has captured fresh images of Saturn and Mars as they approach opposition – the point in their orbit when the planets are at their closest to Earth, and fully illuminated by the light of our star. Saturn and its rings can be seen shining clearly in the new portrait, while the features of Mars are wreathed by a planet-encompassing dust storm.
Despite getting off to a rocky start courtesy of an improperly-ground primary mirror, the Hubble Space Telescope has done nothing but inspire and amaze us in the decades since its launch in April 1990. The observatory has lavished us with breath-taking images of the cosmos, snapping everything from gorgeous nebulae to colossal galaxies, and almost everything in between.
Whilst the venerable telescope has been invaluable in advancing our understanding of the larger universe, it has also played a crucial role in furthering our knowledge of the planets that make up our home solar system.
From its lofty perch some 574 km (340 miles) above the Earth, Hubble is able to make long-term observations that complement the relatively short-lived efforts of probes, such as Juno and Cassini, which are tasked with studying these disparate worlds in situ.
Every now and again the planets literally align, affording Hubble the perfect conditions to capture detailed images of its distant quarry. This is known as an opposition. Opposition occurs when Earth is positioned with the Sun lined up directly behind it, and an outlying planet, such as Mars, Saturn, or Jupiter, lined up on the opposite side.
This is the ideal opportunity for some planetary photography, as opposition represents the point at which a world is at its closet point to Earth in its orbit, and is also fully lit by the light of the Sun from the perspective of our Blue Marble.
The gas giant Saturn was the first of the two planets to be shot by Hubble as it approached its June 6, opposition relative to the Earth. The new portrait was captured a month before opposition, as Saturn passed a mere 1.4 billion km from the telescope.
Saturn plays host to the largest ring system of any planet in our solar system. The adornment stretches out to the equivalent of roughly eight times the radius of the vast planet, and is thought to have formed from smaller bodies, such as comets, asteroids, and even moons that were torn apart by the destructive force of Saturn's gravity.
In the new portrait, Saturn's rings are tilted heavily towards Earth, highlighting the unique characteristics of the individual rings, and the gaps that separate them, some of which are forged by embedded shepherd moons.
Cloud belts are also clearly distinguishable marking the gas giant's surface, along with the distinctive hexagonal polar vortex, which was spotted first by NASA's Voyager 1 probe back in 1981, and subsequently imaged in greater detail by the Cassini spacecraft.
Below the polar vortex, a series of white clouds are clearly visible, representing the final remnants of a disappearing storm. Hubble was also able to capture six of the gas giant's 62 known moons – Dione, Enceladus, Tethys, Janus, Epimetheus and Mimas.
Hubble's latest image of Mars was snapped only 13 days before its closest approach on July 18. The Red Planet is currently shrouded in a global dust storm, which, alongside obscuring the surface features of the barren world, is also posing a significant risk to NASA's long-serving Opportunity rover.
Whilst the majority of the planet's features are obscured, Mars' substantial polar caps remain visible, as does the Hellas Basin, Terra Meridiani, and the Schiaparelli Crater.
Mars will be at its brightest during opposition, which is set to take place on Friday, and just so happens to coincide with a total lunar eclipse, so be sure to get out there tomorrow after sunset and enjoy a stunning example of celestial mechanics at work.
Scroll down to see an animation of Saturn and its moons, created from Hubble imagery collected over the course of 20 hours.
Source: Hubble Space Telescope
