Solar System

Saturn and Mars at Opposition

July 26, 2018 · NASA

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Hubble’s Latest Portraits of Saturn and Mars

NASA’s Hubble Space Telescope has photographed Saturn, left, and Mars, right, near their closest approaches to Earth in June and July 2018.

The planets were photographed near opposition, when the Sun, Earth and an outer planet are lined up, with Earth sitting in between the Sun and the outer planet.

It’s now summertime in Saturn’s northern hemisphere and spring in Mars’ southern hemisphere. The increase in sunlight in Saturn’s northern hemisphere has heated the atmosphere to trigger a large storm that is now disintegrating in Saturn’s polar region. On Mars, a dust storm has erupted in the southern hemisphere and ballooned into a global dust storm enshrouding the entire planet.

Hubble viewed Saturn on June 6, when the ringed world was approximately 1.36 billion miles from Earth, as it approached a June 27 opposition. Mars was captured on July 18, at just 36.9 million miles from Earth, near its July 27 opposition. This close distance puts Mars at its brightest appearance in the night sky since the 2003 opposition.

Saturn’s portrait is the first image of the planet taken as part of the Outer Planet Atmospheres Legacy (OPAL) project. OPAL is helping scientists understand the atmospheric dynamics and evolution of our solar system’s gas giant planets. The yearly observations from OPAL, expected to last beyond 2025 throughout Hubble's remaining operation, will provide a legacy of time-domain images for use by planetary scientists.

About the colours

This image is a composite of separate exposures acquired by the WFC3/UVIS instrument. Several filters were used to sample various wavelengths. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are: Saturn: Blue: F395N Green: F502N Red: F631N Mars: Purple: F275W Blue: F410M Green: F502N Red: F673N