Astronomy Picture of the Day · December 23, 1999

Unusual Aurora During Solar Wind Dropout

The Astronomy Picture of the Day for December 23, 1999 is “Unusual Aurora During Solar Wind Dropout,” an image. It is credited to Credit: PIXIE, POLAR, NASA. The original explanation runs about 146 words.

From the explanation

“On May 10, for some unknown reason, the Solar Wind virtually stopped. Normally our Sun emits a wind of between five and ten energetic particles per cubic centimeter moving outward at about 500 kilometers per second.”

— APOD editors, December 23, 1999

Read the full explanation on science.nasa.gov

At a glance

Date: December 23, 1999
Type: Image
Credit: Credit: PIXIE, POLAR, NASA
Copyright: No copyright notice on the entry. Check the credited institution’s own usage rules before reusing it.
Explanation length: About 146 words

All of December 1999 → · 1999 by month → · Full archive since 1995 →

Topics in this entry

The Sun Auroras

Topics are matched from words in the title and explanation.

On this day: December 23 in other years

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Source

Astronomy Picture of the Day, December 23, 1999 — science.nasa.gov/image-article/apod-1999-december-23-unusual-aurora-during-solar-wind-dropout

Copy taken Oct 28, 2026, 2:39 AM EDT. The image and explanation belong to their creators. OpenOrbit is not affiliated with or endorsed by NASA.