May 20, 2019

Astro-event of the Week: July 15-21st 2008

Comets are the great surprise packages of the solar system. Often appearing out of nowhere, they can brighten up with surprising rapidity, or unexpectedly fizzle, like Kahoutek did in the 1970s. Hence, astronomers are very reluctant to cry “comet of the century” unless they are very certain.

Comet Boattini may not be “comet of the century” material, but is worth checking out none the less! The nucleus of the comet will be about 20 degrees above the eastern horizon, near the head of the constellation of Cetus, the Whale, about an hour and a half before sunrise. The comet is predicted to be less than a brightness of +6 magnitude, lower than the generally accepted brightness visible to the naked eye. Through binoculars, however, one should discern a fuzzy, globular like coma, and perhaps a short, spikey tail. Fresh from perihelion passage on June 24th, Comet Boattini’s tail now fans out before it, always pointing away from the sun. This week is the prime time to track this comet; the Full Moon begins to interfere on July 18th and will hamper viewing. As stated earlier, comets are historically notoriously unpredictable; witness Comet Holmes’ bizarre outburst in the fall of last year. Give it a look!

This weeks astro-word of the week is Eccentricity. All objects, the earth included, do not travel in perfect egg shaped paths around the sun, but instead follow egg-shaped paths, known in geometry as ellipses. Ellipses have two center points, known as focii. The eccentricity of the orbit is a function of the ratio between the distance between the foci and the semi-major axis of the orbit; an ellipse with a low eccentricity, such as that of the Earth (0.0167) is nearly circular, while a cometary orbit such as Comet Boattini has an eccentricity of 1.00018, and  is actually an open ended hyperbola. This means that the comet either came in from interstellar space or was nudged out of the distant Oort cloud.  Now,  this particular comet is on a 36,000 year orbit; any comet entering the inner solar system has about a 40% chance of having its orbit significantly altered by Jupiter on its interior passage!

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  1. [...] are still highly speculative, as we seem to have caught this one in outburst… hey, remember Comet Holmes back about a decade ago in 2007? One can only [...]

  2. [...] are still highly speculative, as we seem to have caught this one in outburst… hey, remember Comet Holmes back about a decade ago in 2007? One can only [...]

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