You can now buy the recently released book, Fall of a Thousand Suns: How Near Misses and Comet Impacts affected the Religious Beliefs of our Ancestors. It is available through iBooks and Amazon.


This website only lists information on modern-day comets and meteor showers. The book, however, thoroughly investigates how specific ancient impacts and near misses changed religious beliefs around the world.

Comet Hale-Bopp Orbit

Comet Hale-Bopp


Comet Hale-Bopp Orbit (C/1995 O1)

Comet Hale-Bopp in Oort CloudLocation of Comet Hale-Bopp (red) at its furthest point from the Sun.

Credit: Stellarium (as seen from Sydney, Australia)

Comet Hale-Bopp takes approximately 2,537 year to orbit the Sun.


Although often considered a comet from the Oort Cloud, Comet Hale-Bopp (C/1995 O1) has an orbit that only takes it 360 AU from our Sun.  So Hale-Bopp actually spends most of its life in the scattered disk beyond the Kuiper Belt rather than the Oort Cloud. From the perspective of Earth, this means the comet spends most of its life in the direction of constellation of Pavo (see image to left). Of course, it is far too faint to be seen in Pavo. It only is seen when it enters the inner solar system. At that point, the Sun begins to heat its icy exterior and the comet begins to shed material. This results in a coma, which allows it to be spotted from Earth, and eventually tails.


On July 23,1995 the 10.5 magnitude Hale-Bopp Comet was spotted in the constellation Sagittarius. It was between the orbits of Jupiter and Saturn, and its 37± 12 miles (60±20 km) wide nucleus had begun to expel material.


Don Yeomans, head of NASA's Near Earth Object program at the Jet Propulsion Laboratory, calculated Hale-Bopp’s orbit and believes that it was visible two orbits earlier in the inner solar system was around 2200 BCE.  Brian Marsden suggested that a close call with Jupiter in June of 2215 BCE may have been responsible for the fragmentation of Hale-Bopp into two pieces. Yes, there are two pieces. Hubble Space Telescope observed a second, smaller nucleus nearby.


Why should we listen to anything Brian Marsden had to say?  Well, in the late 1960s Brian wasn’t exactly marching on Washington D.C. to demand a holiday for the Grateful Dead on April 20th.  Instead, Brian was head of the Minor Planet Center, the organization in charge of the database and calculations for all known orbiting comets, asteroids and satellites.


Comet Hale-Bopp orbits through the solar system with an 89.4° degree inclination compared to the ecliptic.


In July of 199 6, a year after its discovery, Comet Hale-Bopp first became visible to the naked eye in the constellation Scotum. The orbit of Hale-Bopp combined with the orbit of Earth, caused the comet to move to Ophiucus in August and September before returning to the north of Scotum by the end of 1996. It grew brighter with each passing day, reaching an apparent magnitude of 2.41 on December 31,1996.


Four simultaneous points of view of the orbit of Comet Hale-Bopp (C/1995 O1). Click on icon in lower right corner to enter full screen HD mode.

Credit: Osamu Ajiki. Modified by Ron Baalke (JPL). Adapted by Kevin Curran.

In January of 1997, Comet Hale-Bopp's orbit took it through Aquila and into Sagitta. By January 31, 1997 it reached an apparent magnitude of 0.79. The comet was now moving extremely rapidly through the constellations and had crossed Cygnus by February 28. It was continuing to grow brighter and had reached an apparent magnitude of -0.99.


In March, the orbit of Comet Hale-Bopp took it through the constellations Lecerta and Andromeda. It grew brighter with each passing day, reaching an apparent magnitude of -1.72 on April 1, 1997 (see image to left). It was the closest Hale-Bopp would ever get to the Sun. This point is space is known as the comet's perihelion.


In April, the Comet Hale-Bopp continued to move quickly. In April, the orbit of Comet Hale-Bopp took it through Perseus and Taurus. Hale-Bopp was now beginning to decrease in brightness. By June, the comet passed through Orion and Monoceros.


On June 31, Comet Hale-Bopp's apparent magnitude was 2.7. Hale-Bopp turned out to be one of the brightest comets in the 20th century and was visible for eighteen months.



Related Links: