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FAQs

Why do volcanoes erupt?

Piton de la Fournaise or “Peak of the Furnace” on Reunion Island is one of the world’s most active volcanoes, shown erupting in August 2015. Photo credit: AAP/NewZulu/Vincent Dunogué

Piton de la Fournaise or “Peak of the Furnace” on Reunion Island is one of the world’s most active volcanoes, shown erupting in August 2015. Photo credit: AAP/NewZulu/Vincent Dunogué

Some people believe volcanic eruptions are caused by fate. Others believe a volcanic eruption is a sign that a mountain is upset because residents living nearby have sinned. But science has another explanation.

How to spot the International Space Station

ISS crossing the sky in a long-exposure photograph by Antonín Hušek?.

ISS crossing the sky in a long-exposure photograph by Antonín Hušek?.

Every so often, the International Space Station (ISS) becomes visible in your night sky. It’ll look like a bright star moving quickly above the horizon. The ISS is so bright, it can even been seen from the center of a city. Here’s how you can spot the ISS in your night sky.

Dates of sun’s entry into each Zodiac constellation

leo-constellation-regulus

On August 11, 2015, the sun enters the constellation Leo the Lion, and has its annual conjunction with the star Regulus on August 23. Dates of sun’s entry into each zodiacal constellation and the corresponding ecliptic longitude (sun’s position in degrees, east of the March equinox point), inside.

When is the next supermoon?

What most call a Blue Moon isn't blue in color. It's only Blue in name. This great moon photo from EarthSky Facebook friend Rebecca Lacey in Cambridge, Idaho.

Moon photo is from Rebecca Lacey in Cambridge, Idaho.

According to the definition of supermoon coined by Richard Nolle 30 years ago, the year 2015 has a total of six supermoons. They are the new moons of January, February and March and the full moons of August, September and October. The September 28, 2015 full moon will be the closest supermoon of 2015.

What’s the birthstone for August?

Peridot

Peridot

Happy birthday to our August friends! This is one of your birthstones, peridot. Your other birthstone is sardonyx.

Read about both of your birthstones….

What is virga?

Virga over west Texas by Deborah Byrd.

Virga over west Texas by Deborah Byrd.

We’ve all seen virga, but maybe not known what it’s called. Virga is rain that evaporates before it hits the ground. Enjoy these photos!

How to see a green flash

San Diego, California on October 25, 2012, taken by EarthSky Facebook friend Jim Grant.  Thanks Jim!

San Diego, California on October 25, 2012, taken by EarthSky Facebook friend Jim Grant. Thanks Jim!

It’s said that once you’ve seen a green flash, you’ll never go wrong in matters of the heart. Here’s all you need to know to see the legendary green flash, plus great pics.

What makes Venus the brightest planet?

View larger. | Venus and Jupiter (with moons) on June 30 by Geraint Smith in Taos, New Mexico.

Venus and Jupiter (with moons) on June 30, 2015 by Geraint Smith in Taos, New Mexico.

Venus is bright because it’s nearby, because it’s blanketed in highly reflective clouds and because of its location in orbit with respect to Earth now.

How to see anticrepuscular rays

Anticrepuscular rays and a rising moon caught by Jenney Disimon in Sabah, North Borneo on June 4, 2015.

Jenney Disimon in Sabah, North Borneo caught these anticrepuscular rays and a rising moon – and posted them to EarthSky Facebook – on June 4, 2015.

Next time you see crepuscular rays or sunrays extending from the horizon … turn around. You might catch a glimpse of elusive anticrepuscular rays.

How do fireworks get their colors?

Photo credit: Jeff Golden

Photo credit: Jeff Golden

If you’re celebrating the 4th of July by attending a fireworks display, maybe you’ll look up and wonder: What creates those red, orange, yellow, green, blue and purple colors exploding in the night sky?