Hopefully Monday 21st night sky will be clear. If so look out for for the “Christmas Star Over Winstanley”. The star is a result of the bright planets Jupiter and Saturn being closest together since 1623 and in our line of sight. We understand that it is easily visible in the evening sky over two weeks, with the best views being on Monday December 21st.
Dependant on the night time sky and cloud, you should be able to see it due to the brightness. If looking before the sun has set, do not look directly at the setting sun without a filter.
How to find the Christmas Star Over Winstanley
Try the following;
- Find somewhere with an unobstructed view of the sky, such as a field or park. Jupiter and Saturn are bright, so they can be seen even from towns where there is a lot of light pollution.
- An hour after sunset, look to the southwestern sky. Jupiter will look like a bright star and be easily visible. Saturn will be slightly fainter and will appear slightly above and to the left of Jupiter until December 21, when Jupiter will overtake it and they will reverse positions in the sky.
- The planets can be seen with the unaided eye, but if you have binoculars or a small telescope, you may be able to see Jupiter’s four large moons orbiting the giant planet.
Each night, the two planets will appear closer low in the southwest in the hour after sunset.
A Bit of History
In 1610, Italian astronomer Galileo Galilei discovered the four moons of Jupiter; Io, Europa, Ganymede, and Callisto. In that same year, he discovered Saturn’s rings. In 1623, the solar system’s two giant planets, Jupiter and Saturn, travelled together across the sky. Jupiter caught up to and passed Saturn, in a Great Conjunction.
What Will you See?
In the words of Henry Throop, an astronomer in the Planetary Science Division at NASA Headquarters: “You can imagine the solar system to be a racetrack, with each of the planets as a runner in their own lane and the Earth toward the centre of the stadium. From our vantage point, we’ll be able to be to see Jupiter on the inside lane, approaching Saturn all month and finally overtaking it on December 21.”
The planets regularly appear to pass each other in the solar system, with the positions of Jupiter and Saturn being aligned in the sky about once every 20 years. However it’s been nearly 400 years since the planets passed so close to each other in the sky, and nearly 800 years since the alignment of Saturn and Jupiter occurred at night.
The closest alignment will appear just a tenth of a degree apart and last for a few days.
From our vantage point on Earth the huge gas giants will appear very close together, but they will remain hundreds of millions of miles apart in space. And while the conjunction is happening on the same day as the winter solstice, the timing is merely a coincidence, based on the orbits of the planets and the tilt of the Earth.
“Conjunctions like this could happen on any day of the year, depending on where the planets are in their orbits,” said Throop. “The date of the conjunction is determined by the positions of Jupiter, Saturn, and the Earth in their paths around the Sun, while the date of the solstice is determined by the tilt of Earth’s axis. The solstice is the longest night of the year, so this rare coincidence will give people a great chance to go outside and see the solar system.”