heic0904 - Photo Release

Four of Saturn's moons parade by their parent

17 March 2009

A new Hubble image shows four of Saturn's moons circling the ringed planet

On 24 February 2009, the NASA/ESA Hubble Space Telescope captured a photo sequence of four moons of Saturn passing in front of their parent planet. The moons, from far left to right, are the white icy moons Enceladus and Dione, the large orange moon Titan, and icy Mimas. Due to the angle of the Sun, they are each preceded by their own shadow.

These rare moon transits only happen when the tilt of Saturn's ring plane is nearly "edge on" as seen from the Earth. Saturn's rings will be perfectly edge on to our line of sight on 10 August and 4 September 2009. Unfortunately, Saturn will be too close to the Sun to be seen by viewers on Earth at that time. This "ring plane crossing" occurs every 14-15 years. In 1995-96 Hubble witnessed the previous ring plane crossing, as well as many moon transits, and helped to discover several new moons of Saturn.

Early 2009 was a favourable time for viewers with small telescopes to watch moon and shadow transits crossing the face of Saturn. Titan, Saturn's largest moon, crossed Saturn on four separate occasions: 24 January, 9 February, 24 February and 12 March, although not all events were visible from all locations on Earth.

Italian Galileo Galilei — often referred to as the father of astronomy — was the first to observe Saturn through a telescope in 1610. Dutch mathematician and astronomer Christian Huygens discovered Titan in 1655 and, 350 years later, the ESA probe named for him touched down on Titan (on 14 January 2005), giving the world its first views of the surface of the mysterious, icy world. Giovanni Domenico Cassini, a French/Italian astronomer, discovered Dione (in addition to others) and the German-born Englishman, William Herschel, discovered Mimas and Enceladus.

These pictures were taken with Hubble's Wide Field Planetary Camera 2 on 24 February 2009, when Saturn was at a distance of roughly 1.25 billion kilometres from Earth. Hubble can see details as small as 300 kilometres across on Saturn. The dark band running across the face of the planet slightly above the rings is the shadow of the rings cast on the planet.

Notes

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

Image credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA)

Links

NASA's release

Contacts

Colleen Sharkey
Hubble/ESA, Garching, Germany
Tel: +49-89-3200-6306
Cell: +49-151-153-73591
E-mail: csharkey@eso.org

Ray Villard
Space Telescope Science Institute, Baltimore, Md.
Tel: +1-410-338-4514
E-mail: villard@stsci.edu

Keith Noll
Space Telescope Science Institute, Baltimore, Md.
Tel: +1-410-338-1828
E-mail: noll@stsci.edu

About the Release

Release No.:heic0904

Images

Quadruple Saturn moon transit snapped by Hubble
Quadruple Saturn moon transit snapped by Hubble
Quadruple Saturn moon transit snapped by Hubble
Quadruple Saturn moon transit snapped by Hubble
Quadruple Saturn moon transit snapped by Hubble
Quadruple Saturn moon transit snapped by Hubble
Quadruple Saturn moon transit snapped by Hubble
Quadruple Saturn moon transit snapped by Hubble
Quadruple Saturn moon transit snapped by Hubble
Quadruple Saturn moon transit snapped by Hubble
Quadruple Saturn moon transit snapped by Hubble
Quadruple Saturn moon transit snapped by Hubble
Compass and scale image of Saturn
Compass and scale image of Saturn
Annotated image of Saturn's rings and moons
Annotated image of Saturn's rings and moons
Photo sequence of Saturn: 24 February 2009
Photo sequence of Saturn: 24 February 2009
Saturn's rings viewed from Earth
Saturn's rings viewed from Earth

Videos

Four of Saturn's moons parade by their parent (artist's impression)
Four of Saturn's moons parade by their parent (artist's impression)

Text

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