Archers Comet

The nucleus of Archer's Comet

Archers Comet approached by Enterprise

Enterprise passes the tail of Archer's Comet

Archers Comet surface

The surface of Archer's Comet

Archer's Comet was a comet discovered by Enterprise NX-01 in June of 2151. With a diameter of 82.6 kilometers, the comet was the largest ever observed by Humans.

As a comparison, optimistic estimates place the diameter of the nucleus of Hale-Bopp at 60 ± 20 kilometers.

Initially disregarded as merely "rock and ice" by Sub-Commander T'Pol, upon further analysis it was discovered to contain large quantities of eisillium located under a twenty-meter thick layer of magnesite. Since eisilium was extremely rare, Captain Archer suggested obtaining a sample with the transporter. With the layer located out of transporter range, Lieutenant Reed suggested making use of the portable drilling rig with Ensign Mayweather's assistance.

During the "comet walk," the drilling team experienced several setbacks, including a broken drill bit due to a layer of magnesite, a rotational axis shift resulting in the dawn approaching sooner than expected causing the temperature to increase by several hundred degrees, and the shuttlepod falling into a chasm due to melting ice. Enterprise attempted to use the grappler and pull the shuttlepod to safety. However, a secure hold could not be obtained. The drilling team was eventually rescued by the Vulcan ship Ti'Mur. (ENT: "Breaking the Ice")

Scans of the comet were reported by Enterprise to Starfleet Headquarters, where Admiral Forrest found them "incredible." He later relayed this enthusiasm to Archer. (ENT: "Fortunate Son")

In the writers' second draft script of "Breaking the Ice", this comet was instead named "Comet Archer" and was said to have a diameter of forty-eight point six kilometers. It was described as having been traveling through space for the past ten billion years and be scheduled to orbit within fifty kilometers of its sun in twenty-seven days since its discovery by Enterprise. Also, it was theorized that, during the past ten billion years, the comet had orbited around its sun only a few times.
In the first draft script of "Fortunate Son", Archer mentioned that the scans of the comet didn't do justice to actually seeing the comet in person, and Admiral Forrest wrily answered he had been told the comet would be visible from Earth in approximately ten thousand years.
According to the reference book Star Trek: Star Charts (p. 60), this comet was discovered by the Enterprise in the Beta Quadrant.