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The secrets of night-shining clouds

Noctilucent clouds captured from Soomaa National Park, Estonia, in 2009. Image via Martin Koitmäe via Wikimedia Commons.

What are noctiilucent clouds? Glowing silver-blue clouds that sometimes light up summer night skies in polar regions, after sunset and before sunrise, are called noctilucent or “night-shining” clouds. Scientists studying these clouds have found that year-to-year changes in them are closely linked to weather and climate across the globe.

It’s summer. What’s noon to you?

Photo by EarthSky Facebook friend Muhammad Mohsin Jameel.  He wrote,

Photo posted June 21, 2013 by EarthSky Facebook friend Muhammad Mohsin Jameel. He wrote, “Shortest shadows at noon, summer solstice! — in Islamabad, Pakistan.” Thank you Muhammad!

When is it noon for you? That’s really not as easy a question to answer as you might think! What do you mean by noon? Do you define it by your clock or wristwatch? Or the gnawing in your stomach that says it’s time for lunch? Well, you might want to think again!

The summer solstice as seen from Stonehenge

EarthSky Facebook friend Buddy Puckhaber of South Carolina took this photo of Stonehenge in the early morning, while visiting.  He said,

EarthSky Facebook friend Buddy Puckhaber of South Carolina took this photo of Stonehenge in the early morning, while visiting. He said, “My wife and I were among the first visitors of the day.” Thank you, Buddy! Used with permission.

It’s summer solstice time for us in the Northern Hemisphere. This solstice occurs at the instant the sun reaches its most northerly point on the celestial sphere, the imaginary sphere of stars surrounding Earth. If you stood inside the Stonehenge monument on the day of the northern summer solstice, facing north-east through the entrance towards a rough hewn stone outside the circle – known as the Heel Stone – you would see the sun rise above the Heel Stone, as illustrated in the image above. To see more photos of Stonehenge, click inside.

Watching solstices and equinoxes from space

Earth's seasons result from the tilt of our planet's axis with respect to our orbit around the sun.  Upper left: northern winter.  Lower left: northern summer.  The images on the right show equinoxes.  Images via NASA

Earth’s seasons result from the tilt of our planet’s axis with respect to our orbit around the sun. Upper left: northern winter solstice. Lower left: northern summer solstice. Upper right: northern spring equinox. Lower right: northern autumnal equinox. Images via NASA

Why does Earth have seasons? It’s natural to think our world’s seasons result from Earth’s changing distance from the sun. But you can easily see that’s not the case, when you realize that Earth is farther from the sun in July (northern summer) and closer in January (northern winter). The fact that Earth’s Northern and Southern Hemispheres have their summers and winters at opposite times of the year provides a clue to the real reason for seasons: that reason is Earth’s 23-and-a-half-degree tilt on its axis. The photos and video on this page – from NASA – show Earth’s solstices and equinoxes from space.

Celebrate solstice sun by viewing this cool solargraph

This solargraph is a single long-exposure photo of the sun over a six-month period, between the December solstice of 2009 to the June solstice of 2010.  Image by APEX Telescope via Wikimedia Commons

This solargraph is a single long-exposure photo of the sun over a six-month period, between the December solstice of 2009 to the June solstice of 2010. Image by APEX Telescope via Wikimedia Commons

A solargraph, like this one, is a long-exposure photograph that shows the path taken by the sun across the sky, over time. In this case, the time period is the six months between the December solstice of one year and June solstice of the next. The streaks in the photos are sun-trails – the sun moving in its shifting path across the sky from day to day over that six-month interval.

Way cool real-time U.S. wind map

U.S. wind map on June 19, 2014 at 6:58 a.m. CST.  Top wind speed: 24.9 mph.  Average wind speed: 6.5 mph.  Via hint.fm/wind

U.S. wind map on June 19, 2014 at 6:58 a.m. CST. Top wind speed: 24.9 mph. Average wind speed: 6.5 mph. Via hint.fm/wind

Watch the wind flowing across the U.S. in real time. It’s interesting, and it’s also beautiful. It’s a moving wind map that updates every hour and lets you see the movement, flow, and speeds of wind across the United States. What’s above is a still image from the wind map. The real one moves in a way reminiscent of actual wind. It updates hourly.

Lifeform of the Week: Eels, cuter than you think?

Image Credit: Damien du Toit

Image Credit: Damien du Toit

Let go of your aversion to slimy animals and embrace the eel appeal.

A Chinese perspective on summer

Looking for a new perspective on the summer solstice – or some new ways to celebrate? Try these ideas, from Chinese thought.

Monster twin tornadoes strike Pilger, Nebraska

Via Shalyn Phillips  (@ShayJo13 on Twitter)

Tornadoes near Pilger, Nebraska on June 16, 2014 via Shalyn Phillips (@ShayJo13 on Twitter)

Yesterday’s severe weather outbreak across parts of the U.S. Midwest resulted in damaging winds, large hail, and tornadoes and produced over 400 storm reports. Conditions were favorable for strong tornadoes, which are typically classified as EF-2 or stronger. Footage of twin tornadoes appeared both on television and through social media. The city of Pilger, Nebraska was hit the hardest as tornadoes ripped through the city, injuring over 15 people and killing one. Governor Dave Heineman declared a state of emergency as tornadoes hit multiple counties in the state of Nebraska yesterday. Click inside for more info, images and video.

Seeing things that aren’t there

Pareidolia of an Apache head in rocks, in Ebihens, France via Wikimedia Commons.

Erwan Mirabeau shot this rock formation in Ebihens, France. It’s clearly reminiscent of a green haired man, known in the area as an Apache. It’s an example of pareidolia. Photo via Wikimedia Commons.

Maybe you’ve seen the proverbial bunny in a patch of clouds, or a clown’s face in a mud splatter on the side of your car? Seeing or hearing recognizable objects or patterns in otherwise random or unrelated objects or patterns is called pareidolia. Everyone experiences it from time to time – some people more than others. Look at the photos inside to learn more and test your own ability to see things that aren’t there.