April 8, 2013
Saturn’s Moon Telesto Discovered 33 Years Ago Today
Lee Rannals for redOrbit.com — Your Universe Online
Thirty-three years ago today, astronomers discovered Saturn's moon Telesto using ground-based observations.
Astronomers Bradford A. Smith, Harold Reitsema, Stephen M. Larson and John W. Fountain were performing ground observations on April 8, 1980 when they discovered the Saturn moon. The moon was officially named after Telesto of Greek mythology, but was also designated as Saturn XIII or Tethys B.
NASA said Telesto is known as Tethys Trojan because it circles Saturn in the same orbit as the moon Tethys. Telesto orbits about 60 degrees ahead of Tethys and Calypso orbits behind Tethys by about 60 degrees. The relationship between Telesto and Tethys was first identified by Seidelmann, P. K in 1981.
Telesto and Calypso are known as Trojan moons because they are both moons of the Tethys moon that orbits Saturn. Saturn has two other Trojan moons in its systems, hosted by the moon Dione.
Telesto is about 15 miles across and has a smooth, icy surface. NASA said that it does not show the signs of intense cratering like what is seen on many of Saturn's other moons.
Cassini snapped an image of Telesto back in 2005 as it flew by the Trojan moon. The spacecraft took the image in polarized green light with its narrow-angle camera on October 11, 2005 at about 9,000 miles away. The spacecraft released another image of the moon months before, but Telesto was just a spec seen hanging underneath Saturn's rings.
Cassini has helped provide scientists with plenty of views of Saturn's many moons. Just recently the spacecraft released an image of Saturn's moon Rhea. It was the last close flyby of the moon for the mission. This flyby allowed scientists to gather information about the gravitational pull of Rhea to help understand whether the moon is homogeneous all the way through, or whether it has differentiated into the layers of core, mantle and crust. The spacecraft flew within 600 miles of the surface on March 9, completing its fourth close flyby of the Saturn moon.
The Cassini spacecraft launched on October 15, 1997 from Cape Canaveral Air Force Station using a US Air Force Titan IVB/Centaur launch vehicle. Since then it has provided a plethora of data for scientists to use to analyze the solar system's largest ringed planet.