An artist?s rendition of the Huygens probe, headed for Saturn?s moon, Titan. (Reuters)

Don?t be surprised to see a bright golden object in the Thursday evening sky. It?ll be Saturn, at its closest to the earth until 2031.

A clear sky over Calcutta permitting, Saturn will be visible to the naked eye between 5.07 pm on Thursday and 6.29 am on Friday. It will be directly overhead at 11.46 pm.

As astrologers scurry to pin dire predictions on the turn that Saturn will take, the astronomical explanation is as clear as the Wednesday evening sky over the city was murky.

Saturn came as close as 1.1968 billion km to earth on December 31, 2003. On the night of January 13, it will be a shade further away, at 1.2012 billion km.

?But the planet will not come so close for another 26 years,? says Debiprosad Duari, director, research & academics, MP Birla Planetarium.

Amateur astronomers can use a three-inch-diameter telescope to observe the rings and even the moons of Saturn, according to the planetarium.

The ringed planet will be at ?opposition? on the night of January 13 and 14, when the sun, the earth and Saturn form a straight line. ?The opposition takes place after every one year and 15 days,? adds Duari.

The phase angle between Saturn, the earth and the sun will become almost zero during opposition, making them appear in a straight line. In 2020, a similar linear alignment will take place.

January 13 is also when the Huygens probe of Nasa?s Cassini spacecraft lands on Titan, Saturn?s largest moon.

A joint endeavour of European Space Agency, Nasa and the Italian space agency Agenzia Spaziale Italiana, the largest inter-planetary spacecraft was sent to study the Saturnian system over a four-year period.

Named after Christiaan Huygens, a Dutch scientist who discovered Saturn?s rings and Titan, and Italian Jean-Dominique Cassini, who discovered Saturnian satellites, the mission was launched on October 15, 1997, from Cape Canaveral, USA.

The Huygens probe will be the first to land on a world in the outer solar system and data from Cassini and Huygens may offer clues about how life began on earth.