The interstellar comet 3I/ATLAS is just a day away from perihelion, which is its closest point to the sun and the time around which it is expected to be most active. Although 3I/ATLAS is currently hidden from view from Earth, flying behind the sun, spacecraft elsewhere in the solar system still have the comet in their sights.

Perihelion for 3I/ATLAS takes place on Oct. 30, when the interstellar interloper will be 1.35 astronomical units (125 million miles, or 202 million kilometers) from the sun. (One astronomical unit is the average Earth-sun distance — about 93 million miles, or 150 million km.)

Perihelion is the point in an object's orbit where it is closest to the sun. For comets on highly eccentric orbits, as opposed to planets on near-circular orbits, the effect of perihelion can b

See Full Page