N. Achilleos

Learn More
The magnetic field signature obtained by Cassini during its first close encounter with Titan on 26 October 2004 is presented and explained in terms of an advanced model. Titan was inside the saturnian magnetosphere. A magnetic field minimum before closest approach marked Cassini's entry into the magnetic ionopause layer. Cassini then left the northern and(More)
After 3 years and 31 close flybys of Titan by the Cassini Orbiter, Titan was finally observed in the shocked solar wind, outside of Saturn's magnetosphere. These observations revealed that Titan's flow-induced magnetosphere was populated by "fossil" fields originating from Saturn, to which the satellite was exposed before its excursion through the(More)
Cassini's successful orbit insertion has provided the first examination of Saturn's magnetosphere in 23 years, revealing a dynamic plasma and magnetic environment on short and long time scales. There has been no noticeable change in the internal magnetic field, either in its strength or its near-alignment with the rotation axis. However, the external(More)
[1] The oppositely directed magnetic field in the kronian magnetic tail is expected eventually to reconnect across the current sheet, allowing plasma to escape in an anti-solar direction down the tail. This reconnection process accelerates ions and electrons both toward and away from the planet, allowing the magnetotail to relax to a more dipolar(More)
[1] The long-term statistical behavior of the large-scale structure of Saturn’s magnetosphere has been investigated. Established statistical techniques for Jupiter have been applied to the kronian system, employing Cassini magnetometer data and a new empirical shape model of the magnetopause based on these data. The resulting distribution of standoff(More)
tunity to observe the effects of a sizable cometary collision on a major planet. But uncertainties as to the exact sizes The observation of Comet Shoemaker–Levy 9’s collision with and densities of the impacting fragments (Weaver et al. Jupiter in July of 1994 by the United Kingdom Infrared Telescope (UKIRT) produced spectroscopic data of high quality. 1995,(More)
McConnell and Majeed 1991), and its presence had been inferred from Voyager particle data (Hamilton et al. 1980). We present the results of a spectroscopic study of the H3 infrared emissions of Jupiter, obtained using the United KingFrom the standpoint of molecular physics, the detection of dom Infrared Telescope (UKIRT) on Mauna Kea, Hawaii, durthe H 3(More)
The majority of planetary aurorae are produced by electrical currents flowing between the ionosphere and the magnetosphere which accelerate energetic charged particles that hit the upper atmosphere. At Saturn, these processes collisionally excite hydrogen, causing ultraviolet emission, and ionize the hydrogen, leading to H(3)(+) infrared emission. Although(More)
Planetary aurorae are formed by energetic charged particles streaming along the planet's magnetic field lines into the upper atmosphere from the surrounding space environment. Earth's main auroral oval is formed through interactions with the solar wind, whereas that at Jupiter is formed through interactions with plasma from the moon Io inside its magnetic(More)
The discovery of water vapour and ice particles erupting from Saturn's moon Enceladus fuelled speculation that an internal ocean was the source. Alternatively, the source might be ice warmed, melted or crushed by tectonic motions. Sodium chloride (that is, salt) is expected to be present in a long-lived ocean in contact with a rocky core. Here we report a(More)