Watching comet 67P come back
What the 2015 and 2021 returns looked like from Earth, and what to expect when periodic comets come round again.
Published 2026-10-23
Comet 67P returns to the inner Solar System about every 6.4 years.[1] Most returns are faint, but the geometry is not always the same, and that makes a big difference.
2015: close to the Sun, far from us
In September 2014 the nucleus was only about magnitude 20. Perihelion came on August 13, 2015, but from December 2014 to September 2015 the comet stayed within 45° of the Sun in our sky, and on February 10, 2015 it was just 5° from the Sun and 3.3 AU from Earth.[2] Not an easy year for backyard observers.
2021: the best view since 1982
The 2021 return was better. Perihelion came on November 2, 2021, and the closest approach to Earth followed on November 12 at about 61 million km. The comet reached about magnitude 9, visible in amateur telescopes, and two outbursts were recorded around perihelion.[2]
How to observe a periodic comet
- Get an ephemeris. Positions change night to night; JPL’s database provides orbital elements that planetarium apps use.[1]
- Expect a fuzzy star. A small coma, often with little visible tail at magnitude 9–10.
- Use a camera. Stacked exposures reveal a faint coma that the eye misses, and comparing frames taken an hour apart shows the motion.
- Watch for outbursts. Comets can brighten suddenly, as 67P did twice in 2021.[2]
Periodic comets also lose material at each return, so future appearances can differ from past ones.[5]
Numbered citations link to the sources list on the 67P/Churyumov–Gerasimenko overview page.