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Joliet Junior College Comet P2016 J3 Orbits of Comets Analysis


(a) Comet:

P/2016 J3 (STEREO) STEREO 0.8814 3.9467 7.8408

Scroll horizontally to see the values of orbital eccentricity, semi-major axis length, and orbital period.

(b) Search the internet for information about your comet. Very important: You may come across comets whose names are similar, but not identical to yours. Please use the full name of your comet to check that the information you find is of your comet, not another comet!

(c) Provide a brief description of your comet, that is, give some more information than is in the table below. Write in your own words, and list all your sources, including URLs of websites.

Here are some suggestions of what you could include in your description:

you can write about when your comet last came close to the Sun and when it will come close to the Sun next, if it has been visible to the naked eye or with a telescope, if it has been seen from the northern hemisphere or southern hemisphere, what sort of tail did it have if it came close to the Sun – small, big, changing tail; if your comet been observed to come close to the Sun once or more than once.

(e) The values of orbital eccentricity, semi-major axis length, and orbital period for your comet need to be put into context. One of the ways to doing this is to compare your comet’s properties to that of another comet. Halley’s comet is the comparison comet in this discussion. The eccentricity of Halley’s comet’s orbit is 0.967, the orbit’s semi-major axis length is 17.8 AU and the orbital period is 75.3 years.

Here is your question: How do the orbital eccentricity, orbital semi-major axis length, orbital period, and the shape of your comet’s orbit compare to those of Halley’s comet?

For example: Here is your instructor’s comparison of Earth’s orbit to Halley’s comet’s orbit:

The orbital eccentricity of the Earth is 0.017, which means that the Earth’s orbit is closer to being circular than oval. Halley’s comet has an orbit that is very oval. The two orbital shapes are very different despite the fact that both are ellipses.

The orbital semi-major axis length of the Earth’s orbit is 1 AU. In comparison, Halley’s comet has an orbital semi-major axis length that is closer to that of Uranus’ orbit. The overall size of Earth’s orbit is much smaller than the orbit for Halley’s comet because of the difference in their respective semi-major axis lengths.

The Earth’s orbital period is one year. When compared to Halley’s comet, the Earth travels in its orbit around the Sun 75.3 times in the time that Halley’s comet takes to completes one orbit around the Sun.

Another option to describe your comet’s orbit is to look at a picture of it compared to orbits of solar system planets. You can go to https://ssd.jpl.nasa.gov/sbdb.cgi (Links to an external site.) to view of your comet’s orbit compared to the orbits of the solar system planets. Put your comet’s name in the box on right: e.g. enter “1p” for Halley’s comet. Then click enter on your keyboard. Then click “Orbit Diagram” towards top left to bring up the orbit. You can save screenshots of the orbit diagram using the bottom right button at the top right of the orbit diagram. You can use your mouse to change the orientation of the orbit. Click here (opens in a new tab) for three views of Halley’s comet’s orbit and your instructor’s description of Halley’s comet’s orbit. Note: The orbit diagram of your comet is not the same as a picture of your comet, so do not use an orbit diagram at question (d).

(f) Within one orbital period will your comet experience a large change in speed or a small change in speed and why? Which of Kepler’s Laws helped you arrive at your answer? Which of the orbital properties given in the table helped you to arrive at your answer.

(g) Please include all references to the above questions in your post.

Aside: Here is a link (from Sky and Telescope magazine) to comets that can be seen with an 8-inch telescope during 2021. Most comets are too faint to be seen with a small telescope like an 8-inch one: https://skyandtelescope.org/astronomy-news/observing-news/comet-watch-2021/

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