Halley's Comet in the context of "Star of Bethlehem"

Orion is a prominent set of stars visible during winter in the northern celestial hemisphere. It is one of the 88 modern constellations; it was among the 48 constellations listed by the 2nd-century AD/CE astronomer Ptolemy. It is named after a hunter in Greek mythology.

Orion is most prominent during winter evenings in the Northern Hemisphere, as are five other constellations that have stars in the Winter Hexagon asterism. Orion's two brightest stars, Rigel (β) and Betelgeuse (α), are both among the brightest stars in the night sky; both are supergiants and slightly variable. There are a further six stars brighter than magnitude 3.0, including three making the short straight line of the Orion's Belt asterism. Orion also hosts the radiant of the annual Orionids, the strongest meteor shower associated with Halley's Comet, and the Orion Nebula, one of the brightest nebulae in the sky.

The Orionids meteor shower, often shortened to the Orionids, is one of two meteor showers associated with Halley's Comet (the other one being the Eta Aquariids). The Orionids are named because the point they appear to come from (the radiant) lies in the constellation of Orion. The shower occurs annually, lasting approximately one week in late October. In some years, meteors may occur at rates of 50–70 per hour.

Orionid outbursts occurred in 585, 930, 1436, 1439, 1465, and 1623. The Orionids occur at the ascending node of Halley's comet. The ascending node reached its closest distance to Earth around 800 BCE. Currently Earth approaches Halley's orbit at a distance of 0.154 AU (23.0 million km; 14.3 million mi; 60 LD) during the Orionids. The next outburst might be in 2070 as a result of particles trapped in a 2:13 mean-motion resonance with Jupiter.

The Eta Aquariids are a meteor shower associated with Halley's Comet. The shower is visible from about April 19 to about May 28 each year with peak activity on or around May 5. Unlike most major annual meteor showers, there is no sharp peak for this shower, but rather a broad maximum with good rates that last approximately one week centered on May 5. The meteors we currently see as members of the Eta Aquariid shower separated from Halley's Comet hundreds of years ago. The current orbit of Halley's Comet does not pass close enough to the Earth to be a source of meteoric activity.

Eta Aquariid outbursts occurred in 74 BCE, 401, 443, 466, 530, 839, 905, 927, and 934. The Eta Aquariid meteor shower was the first to be linked to Halley's comet and is usually two to three times stronger than the October Orionids. The Eta Aquariids are the third strongest annual meteor shower observable at Earth and occur at the descending node of Halley's comet. The descending node reached its closest distance to Earth around 500. Currently Earth approaches Halley's orbit at a distance of 0.065 AU (9.7 million km; 6.0 million mi; 25 LD) during the Eta Aquariids.

On January 28, 1986, Space Shuttle Challenger broke apart 73 seconds into its flight, killing all seven crew members aboard. The spacecraft disintegrated 46,000 feet (14 km) above the Atlantic Ocean, off the coast of Cape Canaveral, Florida, at 16:39:13 UTC (11:39:13 a.m. EST, local time at the launch site). It was the first fatal accident involving an American spacecraft while in flight.

The mission, designated STS-51-L, was the 10th flight for the orbiter and the 25th flight of the Space Shuttle fleet. The crew was scheduled to deploy a commercial communications satellite and study Halley's Comet while they were in orbit, in addition to taking schoolteacher Christa McAuliffe into space under the Teacher in Space Project. The latter task resulted in a higher-than-usual media interest in and coverage of the mission; the launch and subsequent disaster were seen live in many schools across the United States.

The Digital Access to a Sky Century @ Harvard (DASCH) was a project that digitized much of the collection of astronomical photographic glass plate negatives created by the Harvard College Observatory and housed in the collection known as the Harvard Plate Stacks. It was a major project of the Center for Astrophysics | Harvard & Smithsonian. The project digitized nearly all of the direct images in the Harvard Plate Stacks with a total of 429,274 glass plates scanned for the final data release in 2024. The database contributes to the field of time domain astronomy, providing nearly hundred years more of data that may be compared to current observations.

From 1885 until 1992, the Harvard College Observatory repeatedly photographed the night sky using observatories in both the northern and southern hemispheres. Over half a million glass photographic plates are stored in the observatory archives providing a unique resource to astronomers. The Harvard collection is over three times the size of the next largest collection of astronomical photographic plates and is almost a quarter of all known photographic images of the sky on glass plates. Those plates were seldom used after digital imaging became the standard near the end of the twentieth century. The scope of the Harvard Plate Stacks collection is unique in that it covers the entire sky for a very long period of time.

This is a list of comets (bodies that travel in elliptical, parabolic, and sometimes hyperbolic orbits and display a tail behind them) listed by type. Comets are sorted into four categories: periodic comets (e.g. Halley's Comet), non-periodic comets (e.g. Comet Hale–Bopp), comets with no meaningful orbit (the Great Comet of 1106), and lost comets (5D/Brorsen), displayed as either P (periodic), C (non-periodic), X (no orbit), and D (lost).

Many of the earlier comets observed in history are designated with an X or D due to not having the tools to measure a comet's orbit accurately and eventually losing it. X/1106 C1 (the Great Comet of 1106) is a good example. The orbital elements for the older non-periodic comets in the list assume that the comet has an eccentricity of roughly 1; therefore, the calculations are only approximate.