Perihelion is the point in the orbit of a planet or other celestial body where it is closest to the Sun. For Earth, perihelion occurs annually in early January, when the planet is about 147 million kilometers (91 million miles) from the Sun.
Source: ssd.jpl.nasa.gov
21/11/2025

Now outbound after its perihelion or closest approach to the Sun on October 29, Comet 3I/ATLAS is only the third known interstellar object to pass through our fair Solar System. Its greenish coma and faint tails are seen against a background of stars in the constellation Virgo in this view from planet Earth, recorded with a small telescope on November 14. But this interstellar interloper is the subject of an on-going, unprecedented Solar System-wide observing campaign involving spacecraft and space telescopes from Earth orbit to the surface of Mars and beyond. And while the comet from another star-system has recently grown brighter, you'll still need a telescope if you want to see 3I/ATLAS from planet Earth. It's now above the horizon in November morning skies and will make its closest approach to Earth, a comfortable 270 million kilometers distant, around December 19.