Once every 20 years, Jupiter and Saturn nearly cross paths in the sky, and this year, the two largest planets in the solar system will cross paths during the winter solstice.
According to EarthSky, the two planets will be just .1 degree apart at their closest point on December 21. Being so close, the two planets will appear to be roughly the same size as one-fifth a full moon.
According to EarthSky, the December 2020 conjunction of Jupiter and Saturn is the closest the two planets have been to each other in the night sky since 1623.
However, people back then were not able to see the celestial event, because of its proximity to the sun, according to Amy Oliver, a spokeswoman for the Harvard-Smithsonian Center for Astrophysics.
Oliver told The Boston Globe that the last time people would have noticed two planets coming together this closely would have been in 1226, during the Middle Ages, nearly 800 years ago.
Scientists say the two planets will appear in the early evening sky for the rest of 2020 and Jupiter will be the brightest object in the western sky for the rest of the year.