July 17, 2000
The cosmos has been expanding since the beginning of time, making room for galaxies, for stars, for planets — and ultimately, for you.
Lightning on Earth
Birthday · July 17, 2000
A little universe, just for you
Your date.
Ready to give.
Free PNG · 1080 × 1350 · No account needed
Image rights and credit requirements apply when sharing or reusing imagery.
Date & occasion only
Change the year
APOD published July 17, 2000. Credit: Adam Block (KPNO), AURA, NOAO, NSF. A publication-date match, not a photo taken on your date. Independent of NASA.
Nobody knows what causes lightning. It is known that charges slowly separate in some clouds causing rapid electrical discharges (lightning), but how electrical charges get separated in clouds remains a topic of much research. Nevertheless, lightning bolts are common in clouds during rainstorms, and on average 6000 lightning bolts occur between clouds and the Earth every minute. Above, several lightning strokes were photographed behind Kitt Peak National Observatory in Arizona. Lightning has also been found on the planets Venus, Jupiter, Saturn, and Uranus. NASA launched the TRMM mission in 1997 that continues to measure rainfall and lightning on planet Earth.
Image credit: Adam Block (KPNO), AURA, NOAO, NSF