Astronomy Picture of the Day (2007 Oct. 29) A Tale of Comet Holmes Explanation: What's happened to Comet Holmes? A normally docile comet discovered over 100 years ago, Comet 17P/Holmes suddenly became nearly one million times brighter last week, possibly over just a few hours. In astronomical terms, the comet brightened from magnitude 17, only visible through a good telescope, to magnitude 3, becoming visible with the unaided eye. Comet Holmes had already passed its closest to the Sun in 2007 May outside the orbit of Mars and was heading back out near Jupiter's orbit when the outburst occurred. The comet's sudden brightening is likely due to some sort of sunlight-reflecting outgassing event, possibly related to ice melting over a gas-filled cavern, or possibly even a partial breakup of the comet's nucleus. Pictured above through a small telescope last Thursday, Comet Holmes appeared as a fuzzy yellow spot, significantly larger in angular size than Earth-atmosphere blurred distant stars. Although Comet Holmes' orbit will place it in northern hemisphere skies for the next two years, whether it will best be viewed through a telescope or sunglasses remains unknown. Astronomy Picture of the Day (2007 Oct. 29) Erupting Comet Holmes

Astronomy Picture of the Day (2007 Nov. 5) Explanation: Comet Holmes continues to be an impressive sight to the unaided eye. The comet has diminished in brightness only slightly, and now clearly appears to have a larger angular extent than stars and planets. Astrophotographers have also noted a distinctly green appearance to the comet's coma over the past week. Pictured above over Spain in three digitally combined exposures, Comet 17P/Holmes now clearly sports a tail. The blue ion tail is created by the solar wind impacting ions in the coma of Comet Holmes and pushing them away from the Sun. Comet Holmes underwent an unexpected and dramatic increase in brightness starting only two weeks ago. The detail visible in Comet Holmes' tail indicates that the explosion of dust and gas that created this dramatic brightness increase is in an ongoing and complex event. Comet Holmes will move only slightly on the sky over during the next month. Astronomy Picture of the Day (2007 Nov. 5) Comet Holmes Grows a Tail

Astronomy Picture of the Day (2007 Nov. 10) Explanation: A beautiful blue ion tail has become visible in deep telescopic images of Comet Holmes. Pointing generally away from the Sun and also planet Earth, the comet's ion tail is seriously foreshortened by our extreme viewing angle. Still, enthusiastic comet watchers have remarked that on the whole, the compact but tentacled appearance suggests a jellyfish or even a cosmic calamari. This stunning view of the comet's greenish coma and blue tail was recorded on November 4 in clear skies near Budapest, Hungary. The colors are caused by molecules in the tenuous gas, like C2 (green) and CO+ (blue), fluorescing in sunlight. In a more recent development, the dramatic inset is a deep image from L'Aquila in central Italy on November 8, showing the ion tail disconnecting from the comet. Astronomy Picture of the Day (2007 Nov. 10)

Explanation: What's happening to Comet Holmes Explanation: What's happening to Comet Holmes? The rare comet remains visible to the unaided eyes of northern observers as an unusual small puff ball in the constellation of Perseus. A high resolution set of images of the comet's inner coma, taken last week and shown above, reveals significant detail. Close inspection shows numerous faint streamers that are possibly the result of jets emanating from the comet's nucleus. Comet Holmes has remained surprisingly bright over the past week, with luminosity estimates ranging from between visual magnitudes 2 to 3, making it brighter than most stars visible on a dark sky. The above image of Comet Holmes was made with a small automated 0.38-meter telescope hirable over the web for a small fee. Astronomy Picture of the Day (2007 Nov. 13) The Inner Coma of Comet Holmes

Comet is still in a single piece; no break-up; possibly ejection of large fragments 3.4 kilometer in diameter, or 2.1 miles

Advanced Question Chap. 12, Q36 in P326 Jupiter was at oppositon on June 5, 2007. On that date Jupiter appeared to be in constellation Ophiuchus. Approximately when will Jupiter next be at opposition in this same region of the celetial sphere? Explain your answer?

Advanced Question Chap. 12, Q36 in P326 Answer: Jupiter’s sidereal period is about 12 years, which means that Jupiter will be again at exactly the same position in about 12 years, or 2019. However, for the next opposition as seen from the Earth, it takes only a little more than one year. In one year, Earth moves about 360°, and Jupiter moves about 30°. It takes about another 30 days for the Earth to catch up the 30° that Jupiter has moved. Therefore, Jupiter will be at next opposition in about 395 days. The exact synodic period of Jupiter is 398.9 days