ESA Current Affairs

Sun’s core rotates 4 times faster than its surface: Study

A team of researchers have discovered solar seismic waves which revealed that Sun’s core is rotating four times faster than its surface.  Earlier it was assumed that sun’s core rotate at same speed as the surface.

The discovery was made using 16 years of observations from GOLF (Global Oscillations at Low Frequency) instrument on Solar and Heliospheric Observatory (SOHO) spacecraft, a joint project of ESA and NASA.

Key Facts

Researchers had use ‘Helioseismology’ to probe the solar interior by studying sound waves reverberating through it. They had studied surface acoustic waves in the Sun’s atmosphere, some of which penetrate to the Sun’s core, where they interact with low frequency gravity waves (g-waves) known as g-modes that have a sloshing motion.

From those observations, they detected the sloshing motions of the solar core. By carefully measuring the acoustic waves, the researchers precisely determined the time it takes an acoustic wave to travel from the surface to the centre of the Sun and back again.

On the basis of the signature of the g-waves, researchers determined that the g-waves are shaking the structure of the sun’s core. The signature of the imprinted g-waves suggested that the inner core of the Sun is rotating once every week, nearly four times faster than the observed surface and intermediate layers.

Significance of Discovery: The rotation of the Sun’s core may give a clue to how the Sun formed. It may also help to find linkages between the Sun’s core rotation and sunspots.


NASA’s Cassini spacecraft to make final observations of Saturn

NASA’s Cassini spacecraft after studying Saturn, its rings and moons for more than 12 years, has entered in the final year of its epic voyage.

In its epic voyage, the Cassini spacecraft will make the closest-ever observations of the planet. Beginning November 30, 2016 Cassini will make the closest-ever observations of Saturn.

During the final voyage

  • Cassini will be mapping the Saturn’s magnetic and gravity fields with exquisite precision. It will be returning ultra-close views of the Saturn’s atmosphere.
  • Its orbit will be just past the outer edge of the main rings of Saturn. These orbits will be in a series of 20 which are called the F-ring orbits.
  • Cassini will approach to within 7,800 kilometres of the centre of the narrow F ring with its peculiar kinked and braided structure during these weekly orbits.

About Cassini–Huygens

  • Cassini–Huygens is an unmanned spacecraft sent to the planet Saturn. It is a sophisticated robotic spacecraft orbiting the ringed planet and studying Saturnian system in detail.
  • It is a joint endeavor of NASA, European Space Agency (ESA) and Italian space agency, Agenzia Spaziale Italiana (ASI).
  • Cassini is the 4th space probe to visit Saturn and the 1st to enter successfully in its orbit and its mission is ongoing as of 2016.
  • Its design includes a Saturn orbiter (Cassini) and a lander (Huygens) for the moon Titan. They are named after astronomers Giovanni Cassini and Christiaan Huygens.
  • The spacecraft was launched on 15 October 1997 aboard a Titan IVB/Centaur and it had entered orbit around Saturn on 1 July 2004.
  • On 25 December 2004, Huygens lander had separated from orbiter and landed on Saturn’s moon Titan on 14 January 2005. This was the first landing ever accomplished in the outer Solar System.