Post by Centaur on Aug 30, 2010 23:18:14 GMT -6
Periodic comet 103P Hartley should generate a great deal of public interest this autumn, not only because it may get as bright as magnitude +4.5, but also because NASA’s Deep Impact vehicle is scheduled for a close flyby to study it on November 4. Before that the comet will pass 0.12 AU from Earth on October 20 and then reach perihelion of 1.06 AU from the Sun on October 28.
Prior to 1993 the comet’s perihelion was only 0.95 AU (closer to the Sun than Earth) but a close approach to Jupiter significantly altered its orbital characteristics. Its orbit is inclined only 13.6° to the ecliptic, which enhances the possibility of close approaches to Earth. Its orbital period is only 6.47 years.
This autumn we’ll be treated to a very close approach to Earth of the comet while it is not only near perihelion but also near opposition relative to the Sun. Its path this year is especially advantageous for northern hemisphere observers; right now it is circumpolar for most of us.
I’ve created three related graphics for display on my astronomical webpage. They are for the period from September 18 through December 1 when the comet may be visible for naked eyes. The first plots the positions of the comet in equatorial coordinates. The second shows the horizontal coordinates (alt-az) of the comet as seen from the Chicago’s Adler Planetarium each night at 23:30 CDT. The third is a graph of its stellar magnitude (brightness). They can be seen by clicking www.curtrenz.com/astronomical
Reports and photos of the comet would be welcome additions to this thread.
Prior to 1993 the comet’s perihelion was only 0.95 AU (closer to the Sun than Earth) but a close approach to Jupiter significantly altered its orbital characteristics. Its orbit is inclined only 13.6° to the ecliptic, which enhances the possibility of close approaches to Earth. Its orbital period is only 6.47 years.
This autumn we’ll be treated to a very close approach to Earth of the comet while it is not only near perihelion but also near opposition relative to the Sun. Its path this year is especially advantageous for northern hemisphere observers; right now it is circumpolar for most of us.
I’ve created three related graphics for display on my astronomical webpage. They are for the period from September 18 through December 1 when the comet may be visible for naked eyes. The first plots the positions of the comet in equatorial coordinates. The second shows the horizontal coordinates (alt-az) of the comet as seen from the Chicago’s Adler Planetarium each night at 23:30 CDT. The third is a graph of its stellar magnitude (brightness). They can be seen by clicking www.curtrenz.com/astronomical
Reports and photos of the comet would be welcome additions to this thread.