At this time of year, Christmas trees abound: Real trees, artificial tress, small trees, big trees, scraggly trees, fat and full trees. And while trees for home use rarely top six feet, other trees are stories tall. The famous Christmas tree at 30 Rockefeller Plaza in Manhattan is usually between 75 and 100 feet tall, and requires more than 30,000 energy-efficient LED bulbs to light. But even that tree has nothing on the “Christmas tree” in the night sky.
NGC 2264 is the New General Catalogue designation number for two deep sky astronomical objects: the Cone Nebula, a cloud of space gas shaped like either an ice cream cone or a pine tree, depending on how you look at it, and the Christmas Tree Cluster, a tightly—bunched cluster of about 40 bright blue stars in a vaguely triangular shape, causing them to resemble lights on a Christmas tree.
You can spot these in the winter constellation Monoceros, the unicorn. They are located about 2600 light-years from Earth.
Both objects were first catalogued by astronomer William Herschel on two separate occasions. The cluster made it into his 1784 catalogue. It wasn’t until the day after Christmas in 1785 that Herschel saw the nebula near the cluster’s brightest star. Both objects were conspicuously absent from the famous deep sky object catalogue created by Charles Messier and his assistant Pierre Méchain, first published in 1771.
The very bright Christmas Tree Cluster is easy to spot with a naked eye, as long as the sky is dark enough. The nebula requires binoculars or a telescope to see.