February 27, 2020

17.01.11: Tracking Vestoids.

The American Association of Variable Star Observers & NASA wants YOU to assist them with the up and coming Dawn mission. Specifically, scientists are looking to characterize “Vestoids,” or Vesta-like asteroids in preparation for Dawn’s exploration of the real thing in July of this year. To this end, the AAVSO has selected three targets for amateurs to observe; 1981 Midas (1973 EA), 4688 (1980 WF) and 137052 (1998 VO33). These Near Earth Objects (NEOs) are all thought to be very similar to the asteroid Vesta, and brightness estimates may constrain sizes and compositions.

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An Arctic Moon?

 Everybody knows that north of the arctic circle, the sun can stay above the horizon for months at a time… but what about the Moon? Living in North Pole, Alaska, at latitude 64.5 north for four years, I know that the path of the Moon can do some bizzare things, as well! I decided to run the simulation below in Starry Night to find out;     

Arctic Moon Simulation. (Credit: Starry Night).

Note: If the above link isn’t visible in your browser, click here!

    The site setup for the above video was Alert, Canada at north latitude 82.5 north. The simulation was sped up to x3000 real time speed. Full Moon itself occurs the night of December 12th-13th, but running the Moon through simulation, it never rises or sets! In fact, “moonrise” from Alert is 10:14 AM local on the 7th of December, and “moonset” doesn’t occur until 2:40 PM local on the 17th! This is because during those two weeks, the Moon occupies roughly the same spot on the ecliptic that the Sun does during and around the summer solstice. The phenomena of the midnight sun runs down to about latitude 66.56 degrees north, (just north of Fairbanks, Alaska), but that of the “midnight Moon” runs down to  about latitude 61.42 degrees north, just north of the town of Wasilla (of Palin fame!) Alaska. This is because in addition to the tilt of the Earth, the Moon’s orbit is inclined an additional 5.1 degrees!

   In the southern hemisphere, the same is true, although at opposite times of year… also, keep your eyes out during the time lapse video for a cool occultation of the Pleiades!