Valentine’s Day promises unusual view of Jupiter

Nainital: According to the scientists of NASA, Valentine’s Day this year will witness what Galileo did 400 years ago in early 1610. It is hard to see Jupiter in the evening sky this month, but the northern hemisphere observers may see Jupiter and Venus close together and low on the southwestern horizon on Valentine’s Day. Jupiter’s largest moons were first seen on 7 January in 1610 in Padua, Italy. Galileo looked above the constellation Orion. He aimed his telescope at the well known starry wanderer, the planet Jupiter, which was near Orion that night.
What he saw through his telescope startled him and marked the beginning of modern astronomy. Jupiter was not just one object, as he wrote and drew in his journal. “There are three stars in the heavens moving about Jupiter, as Venus and Mercury around the Sun,” he wrote. Galileo’s observation showed three stars. The one star to the west was Ganymede and to the east there were two objects - one was the moon Callisto and the other was a tight pairing of Io and Europa. Io and Europa appeared so close together that they looked like one object in Gallieo’s modest telescopic view. On 8 January, he saw a different line up altogether. There were three stars on the one side of the planet. lo was the moon closest to the planet, followed by Europa and Ganymede. Two cloudy nights and two additional observations later, on 13 January, Gallieo identified a fourth object orbiting Jupiter. The arrangement this night turned out to be Europa on the east and Ganymede, Io and Callisto on the west. On January 15, all four stars were seen on one side of the planet.