On Monday, 21 Dec. the cosmic alignment of Jupiter and Saturn will create a rare Christmas star known as the Great Conjunction, which hasn't been visible for nearly 800 years. With the next visible alignment not happening until 15 March, 2080, it's well worth catching this elusive Christmas miracle — and we know the best places in London to witness the once-in-a-lifetime event.
To see the Christmas star, you will need to find a clear view of the southwest horizon at twilight (without any trees or buildings in the way), because Jupiter and Saturn will align very low in the sky. Some of the best free spots for viewing the star in London are Primrose Hill in Camden, Parliament Hill at Hampstead Heath, Alexandra Palace, and the Sky Garden. You will have to be at your viewing spot just before 4:30 p.m. (twilight) to have a go at finding the planets floating above the horizon. By around 5:55 p.m., the sky will go completely dark, and the Christmas star should be at its brightest in the sky, but you will need an unobstructed view because the planets will only be two degrees above the horizon at this point and very easy to miss.
Although Jupiter and Saturn should be bright enough to see with the naked eye (assuming the weather will be in our favour), it's recommended to use a pair of binoculars for a much better view. If you're lucky enough to have a small telescope handy, then you might even be able to see Saturn's rings, it's single moon Titan, and the four moons of Jupiter. In the event that you miss the alignment, don't worry! Jupiter and Saturn will remain close together for the remainder of the fourth week of December, right above the southwest horizon for about one hour after sunset (4:30-5:55pm in London).
We hope you catch a glimpse of the Christmas star, but just in case you miss it, Arizona's Lowell Observatory is hosting a free livestream ahead.