This image from NASA’s Cassini spacecraft shows three moons — Rhea (top), Titan and Mimas (bottom). Titan appears fuzzy because we only see its cloud layers and light refracts within its atmosphere, extending the crescent. Image credit: NASA/JPL-Caltech/Space Science Institute.The three moons shown here — Titan (3,200 miles or 5,150 kilometres across), Mimas (246 miles or 396 kilometres across), and Rhea (949 miles or 1,527 kilometres across) — show marked contrasts. Titan, the largest moon in this image, appears fuzzy because we only see its cloud layers. And because Titan’s atmosphere refracts light around the moon, its crescent “wraps” just a little further around the moon than it would on an airless body. Rhea (upper left) appears rough because its icy surface is heavily cratered. And a close inspection of Mimas (centre bottom), though difficult to see at this scale, shows surface irregularities due to its own violent history.
This view looks toward the anti-Saturn hemisphere of Titan. North on Titan is up. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on March 25, 2015.
The view was obtained at a distance of approximately 1.2 million miles (2.0 million kilometres) from Titan where the image scale is 75 miles (121 kilometres) per pixel. Mimas was 1.9 million miles (3.1 million kilometres) away with an image scale of 11.4 miles (18.4 kilometers) per pixel, while Rhea was 2.2 million miles (3.5 million kilometres) away with an image scale of 13.1 miles (21.1 kilometres) per pixel.
A hundred days have passed since Mars was closest to Earth this year, but the Red Planet can still be seen in the early evening sky close to the jewel of the solar system, Saturn. If you wish to identify this pair of planets, then a convenient celestial marker in the form of the waxing crescent Moon passes by on the evenings of 8—9 September in the UK and Western Europe.
If you would like to view ringed planet Saturn at its best but are unsure which ‘star’ you should point your telescope at, no problem — the Moon makes a convenient guide as it brushes close by late into the evening of Monday, June 1st.
Several recent news stories have reported that a mysterious anomaly in the orbit of NASA’s Cassini spacecraft around Saturn could potentially be explained by the gravitational tug of theorised Planet 9, existing far beyond the orbit of Neptune in our solar system. However, NASA cannot find any unexplained deviations in the spacecraft’s orbit.
