news sciences: Start watching for Ursid meteors

Tonight – December 17, 2018 – marks what might be your first night for seeing meteors in the annual Ursid meteor shower. This shower typically peaks around the December solstice, which, in 2018, comes on December 21. The shower’s peak morning is probably December 22, but any of the next few mornings should yield some Ursids as well. The meteor shower usually ends around December 26.

Generally, the Ursids are a low-key affair, offering perhaps as many as 5-10 meteors per hour in a dark sky. In rare instances, bursts of 100 or more meteors per hour have been observed at times, over the past century.

The chart at the top of the page shows the Big and Little Dippers – Ursa Major and Ursa Minor, for whom this meteor shower is named – around 1 a.m. when the Big Dipper is well up in the north-northeast. That’s about the time of night you’ll want to start watching this meteor shower.

Be aware that – in the mornings ahead – the moon will be setting closer and closer to the time of dawn. In 2018, in an uncanny bit of bad timing, the peak of the Ursid shower on the morning of December 22 has to contend with harsh glare of the first December solstice full moon since 2010.

Still! You might see some Ursids.

EarthSky lunar calendars are cool! They make great gifts. Order now. Going fast!

Ursid fireball! A fireball is just a very bright meteor. Eliot Herman in Tucson caught this one on December 18, 2016.

All meteors in annual showers have radiant points on our sky’s dome, and the showers take their names from the constellations in which the radiant points lie. The Ursids radiate from Ursa Minor, which contains Little Dipper asterism. If you trace the paths of the rather slow-moving Ursid meteors backward, they appear to come from the section of sky marked by the Little Dipper star Kochab.

Although the Little Dipper is circumpolar (out all night) at northerly latitudes, the star Kochab sits below Polaris, the North Star, at nightfall. Kochab (and all the Little Dipper stars) circle Polaris in a counterclockwise direction throughout the night, with this star reaching its high point for the night in the hours before dawn. The higher the radiant climbs in your sky, the more meteors that you’re likely to see.

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Ursid meteors radiate from near the star Kochab in the Little Dipper. The star Polaris is also part of the Little Dipper. Can’t find the Little Dipper? Use the Big Dipper! No matter what time of year you look, the two outer stars in the Big Dipper’s bowl always point to Polaris, which marks the end of the handle of the Little Dipper.

Bottom line: If you want to watch the Ursids, find a country location where you can camp out. Dress warmly! And plan to spend several hours reclining under a dark sky. The predawn hours are usually the most favorable – when the full moon is not obtruding on the show.