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Birthday · September 18, 2018

Salt, Pepper, and Ice

September 18, 2018

Every candle on your cake is a tiny imitation of the stars that made you possible.

Salt, Pepper, and Ice

A little universe, just for you

Your date.
Ready to give.

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APOD published September 18, 2018 · Video still. Credit: Maroun Habib (Moophz). A publication-date match, not a photo taken on your date. Independent of NASA.

Behind the image

Salt, Pepper, and Ice

Original APOD · September 18, 2018

There's a "camera" comet now moving across the sky. Just a bit too dim to see with the unaided eye, Comet 21P / Giacobini-Zinner has developed a long tail that makes it a good sight for binoculars and sensitive cameras. The movement of the Comet 21P on the sky was captured last week in the featured time-lapse video compressing 90 minutes into about 2.5 seconds. What might seem odd is that the 21P's tail is not following the comet's movement. This is because comet tails always point away from the Sun, and the comet was not moving toward the Sun during the period photographed. Visible far in the background on the upper left is the Salt & Pepper star cluster, M37, while the bright red star V440 Auriga is visible just about the frame's center. This 2-km ball of dust-shedding ice passed its nearest to the Sun and Earth only last week and is now fading as it crosses into southern skies. Comet 21P should remain visible, however, and photogenic to stabilized cameras, for another month or so.

Image credit: Maroun Habib (Moophz)

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