C/2025 K1

Comet C/2025 K1 (ATLAS) is a recently discovered comet that is expected to become a notable object for observation in late 2025. Here's a breakdown of what we know:

Discovery and Classification:

• It was discovered on May 25, 2025, by the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey in Chile.

• It appears to be a dynamically new comet, meaning it's likely making its first close passage to the Sun.

Orbital Characteristics:

• Perihelion (closest approach to the Sun): October 8, 2025, at a distance of approximately 0.33 AU (Astronomical Units), which is closer than Mercury's orbit. This close approach to the Sun is significant and could lead to substantial brightening.

  • Heliocentric orbit (File: 45.6 MB)

  • Heliocentric, animated 52 weeks (File: 17.6 MB)

• Closest approach to Earth: November 24, 2025 17:00, at a distance of about 0.40 AU or 60 million km. See second image above.

  • Geocentric, closest approach (File: 7.7 MB)

  • Geocentric, closes approach, animated 48 hours (File: 349 KB)

• Eccentricity (e): The orbit is highly eccentric, with a value of 1.000251464554613 (Epoch 2025-Jun-16) , indicating an unbound or nearly parabolic orbit.

• Inclination (i): The orbital plane is highly inclined, 147.864867556013 degrees.

Visibility and Brightness:

• Current Magnitude: As of early July 2025, it's around magnitude 14-15, requiring a telescope for observation.

• Predicted Peak Brightness: It's expected to brighten significantly as it approaches perihelion. Predictions suggest it could reach a magnitude of around 5.2 to 8 in early October 2025.

• Naked-eye visibility: While magnitude 5.2 is generally considered within naked-eye visibility under very dark skies, it's more likely to be a binocular object for most observers, especially at its peak brightness.

• Observing Locations:

  • Early October (near perihelion): Observers in northern latitudes will see it best in the morning sky.

  • Early October (near perihelion): Observers in southern latitudes can spot it in both the evening and morning skies.

  • August: It will be faint (around magnitude 13) and visible only from the Southern Hemisphere through large telescopes.

• Links:

  • The Sky Live observing information

  • NASA JPL Data for C/2025 K1

  • Estimated light curve (magnitude)