A short-period comet that goes round the Sun every 5.3 years, at perihelion about August 2027
Returns in August 2027. First in reach from Georgetown about 18 July to 24 September 2027, with a camera.
Returns in August 2027. First in reach from Georgetown about 18 July to 24 September 2027, with a camera.
From Lethem, under a dark interior sky: Returns in August 2027. First in reach from Lethem about 4 July to 1 October 2027, with a small telescope.
It is not placed for viewing tonight. On its next best night from Georgetown, 30 August 2027, face east (azimuth 74 degrees) at 4:46 am GYT and look low, 15 degrees up. It will be 31 degrees from the Sun.
A window is a run of nights on which it is at least 10 degrees up with the Sun at least 12 degrees down and its forecast brightness reaches a camera or better from Georgetown. The forecast is from how the comet behaved on past returns.
From 3 November 2026 to 9 February 2027 it is hidden in the Sun's glare from Georgetown: 99 nights.
From 11 September to 9 December 2028 it is hidden in the Sun's glare from Georgetown: 90 nights.
| In reach | Best night | Best time | Height and direction | Gear on the best night | Forecast magnitude | Nights at each rung |
|---|---|---|---|---|---|---|
| 18 July to 24 September 2027 | 30 August 2027 | 4:46 am GYT | 15 degrees, east | Camera | about 8.0 (likely 7.2 to 8.8) | 69 camera |
Nobody has reported its brightness to COBS in the last 30 days, so every number here is a forecast.
The forecast comes from past returns (2011, 2016, 2022): a law fitted to 148 eye estimates before perihelion and 228 after, with the Earth's distance at the time removed and this return's put in. Comets do change between returns.
On its best night from Georgetown, 30 August 2027, it could be about 8.0 (likely 7.2 to 8.8), reading 8.8 through the air. Chance of the naked eye: no real chance. Binoculars: no real chance. A small telescope: about 29%. The range is one standard deviation either side: about two forecasts in three land inside it.
A comet's light is spread over a fuzzy patch, so it is harder to see than a star of the same magnitude. That is why the gear rungs ask for a magnitude in hand.
Plan for 30 August 2027: aim at azimuth 74 degrees, altitude 15 degrees, at 4:46 am GYT.
On a fixed tripod keep each exposure short enough that the stars stay round, then stack many frames. For a long stack, align on the comet as well as on the stars: it drifts against them from frame to frame. A dark site adds more than any lens.
45P/Honda-Mrkos-Pajdusakova passes closest to the Sun (perihelion) about 30 August 2027, at 0.559 au, where 1 au is the Earth's distance from the Sun. One orbit takes 5.34 years. The orbit is tilted 4.3 degrees to the Earth's and its eccentricity is 0.8172 (0 is a circle, 1 an open curve).
Orbit: NASA/JPL Horizons osculating elements, solution JPL#K222/7, retrieved 8 October 2026. Positions on this page are computed from them in your browser and agree with JPL's own tables to half an arcminute.
45P/Honda-Mrkos-Pajdusakova is a short-period comet that goes round the Sun every 5.3 years. The "P" in 45P marks a periodic comet, and the number is the order in which its return was first confirmed.
Brightest eye estimate reported to COBS on each past return: 2011: magnitude 6.4, 2 days after perihelion, 0.53 au from the Sun and 0.83 au from Earth; 2016: magnitude 5.9, 7 days after perihelion, 0.55 au from the Sun and 0.56 au from Earth; 2022: magnitude 7.0, 20 days after perihelion, 0.69 au from the Sun and 1.52 au from Earth. How bright a return looks depends as much on how near the Earth it passes as on the comet.
Orbits: NASA/JPL Horizons (Giorgini, JD and the JPL Solar System Dynamics Group), data retrieved 2026-10-08.
Catalogue brightness laws: JPL Small-Body Database and the IAU Minor Planet Center.
Observed brightness: COBS Comet Observation Database (https://cobs.si) and its contributing observers, CC BY-NC-SA 4.0.
Data updated 8 October 2026. "Forecast" means: Not measured yet this return. Based on how this comet behaved on past returns.
Gear rungs and ranges are estimates for a typical observer: your eyes, your sky and the night will differ.