I hope you’re having a warm and wonderful holiday today. Perhaps you’ve already opened your gifts. If so, I’ve got some good news. Christmas isn’t over yet. One package remains to be opened the next clear night — an evening sky comet named 45P/Honda-Mrkos-Pajdusakova. Why the long name? It was discovered by three people all about the same time on December 3, 1948: Japanese astronomer Minoru Honda and Czechoslovakian astronomers Antonin Mrkos and Ludmila Pajdusakova (PIE-doo-sha-ko-vah). Up to three discoverers get to pen their name to a new comet. Pity, if there is a fourth, that person’s out of luck.
The “P” denotes that 45P is a short period comet — one with an orbital period of fewer than 200 years. 45P gets around in a hurry, returning from the far end of its orbit beyond the planet Jupiter to the inner solar system in just 5.25 years. As it glides closer to the sun, the comet exhibits one of its most famous traits: it quickly brightens from a faint puff to a bright, compact ball with a skinny tail. A faint nothing a few weeks back, the 45P is now magnitude +7.5 and visible in 50mm or larger binoculars from a dark site.
For the remainder of December and January, it treks eastward across the center of the constellation Capricornus. While not an especially bright star pattern, we can be grateful for Venus, which glares a little more than a fist to the left and above (east) of the comet. If you’re not sure on where to start looking for the comet, Venus will at least get you pointed in the right direction.
Begin looking for 45P in late dusk just as the last glow of twilight gives way to night. If you wait too long, the comet will set! For the next few weeks, it’s only about one outstretched fist above the southwestern horizon at twilight’s end, and drops lower with each minute of time that passes. In binoculars, the comet will appear as a dim, fuzzy star. A small 4-6 inch telescope will do much better. Look for a fluffy, hazy patch of light with a bright, star-like center. Larger telescopes will show a faint tail spike pointing east. Time exposure photos expand the tail to at least 3° long and reveal the Mediterranean blue hue of the comet’s head or coma. I saw the color straight off when observing the comet several nights ago in my 15-inch reflector at low power (64x).
45P hugs the dusk in the southwestern sky through about Jan. 15. From the 15th till the beginning of February, it hides from view in bright twilight until reappearing at dawn around Feb. 5. I can’t wait for the date. Rapidly pulling away from the sun, 45P will race across the constellations Aquila and Hercules, rising higher and higher into a dark sky.
While the comet reaches perihelion or nearest the sun on Dec. 31, it makes its closest pass of Earth on Feb. 11 at a distance of only 7.7 million miles. On that day, it will zip by our blue globe at over 51,000 miles an hour (23 km/sec). We may even be able to see this little fuzzball with the naked eye then; its predicted magnitude of +6 at maximum hovers right at the naked eye limit. In suburban skies, 45P should be a fairly easy catch in binoculars during the first half of February.
I’ll keep you up to date with new photos and fresh maps as we head into the new year. May all your comets be merry and bright!