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This date in science: New record for youngest moon

View larger. | Youngest possible lunar crescent, with the moon's age being exactly zero when this photo was taken — at the precise moment of the new moon - at 07:14 UTC on July 8, 2013.  Image by Thierry Legault.  Visit his website.  Used with permission.

View larger. | Youngest lunar crescent ever photographed, with the moon’s age being exactly zero when this photo was taken — at the precise moment of the new moon – at 07:14 UTC on July 8, 2013. Image by Thierry Legault. Used with permission.

July 8, 2013. On today’s date a year ago, a new record was set for the youngest moon ever photographed. Thierry Legault – shooting from in Elancourt, France (a suburb of Paris) – captured the July 2013 moon at the precise instant it was new, or most nearly between the Earth and sun for that lunar orbit. Legault’s image shows the thinnest of lunar crescents, in full daylight (naturally, since a new moon is always near the sun in the sky), at 0714 UTC on July 8, 2013.

How do fireworks get their colors?

Photo credit: Jeff Golden

Photo credit: Jeff Golden

Happy Independence Day! 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?

What’s the birthstone for July?

Photo credit:  Shutterstock

Photo credit: Shutterstock

Happy birthday to all you July babies! Your birthstone, the ruby, is among the most highly prized of gemstones. Large rubies are harder to find than large diamonds, emeralds and sapphires. As a result, rubies’ value increases with size more than any other gemstone.

What’s the difference between comets and asteroids?

Comet Lovejoy reflected in the water of Mandurah Esturary near Perth, on December 21, 2011. Image Credit: Colin Legg.

Comet Lovejoy reflected in the water of Mandurah Esturary near Perth, Australia on December 21, 2011. When comets come near the sun, they often sprout glorious tails. Image via Colin Legg.

Asteroids tend to be rockier or more metallic. Comets tend be icier. But some objects blur the distinction between asteroids and comets.

Can you ever see the whole circle of a rainbow?

Double rainbow in Alaska.  Image Credit: Wikimedia Commons

Double rainbow in Alaska. Image Credit: Wikimedia Commons

It is indeed possible to see the whole circle of a rainbow – but conditions have to be just right.

Why isn’t the hottest weather on the year’s longest day?

You know it's hot when ... Image Credit: Flickr user Katerha

The longest day of the year comes at the summer solstice, but the hottest weather always follows a month or two later. Why? The phenomenon of the hot weather following the summer solstice by a month or two is called the lag of the seasons.

How much of the moon can we see from Earth?

Simulated views of the Moon over one month, demonstrating librations in latitude and longitude. Image credit: Tomruen

Simulated views of the moon over one month, demonstrating librations in latitude and longitude. These rocking and wobbling motions as seen from Earth enable us to see more of the moon’s surface than we would otherwise. Image via Tomruen

It’s common knowledge that our moon has a nearside and a farside. One half of the moon always faces Earth, and one half always points away. Does this mean we can only see 50% of the moon’s surface from Earth? No. In fact, over time, it’s possible to see as much as 59% of the moon’s surface, due to a slight north-south rocking and east-west wobbling of the moon known as lunar libration. Follow the links inside to learn more.

Why do fireflies light up?

Here's another cool firefly photo from EarthSky Facebook friend Tom Wildoner.  He said it's a 30-second exposure.  Astrophotographers often capture fireflies when trying to photograph the night sky.

Here’s a cool firefly photo from EarthSky Facebook friend Tom Wildoner. He said it’s a 30-second exposure. Astrophotographers often capture fireflies when trying to photograph the night sky.

Fireflies are sometimes called lightning bugs. Many a child has spent a summer evening chasing them. And maybe you’ve wondered – how and why are these insects able to light up?

How much do oceans add to world’s oxygen?

Phytoplankton - the foundation of the oceanic food chain. image via NOAA

Phytoplankton – the foundation of the oceanic food chain. Scientists estimate that phytoplankton contribute between 50 to 85 percent of the oxygen in Earth’s atmosphere. Image via NOAA

Scientists agree that there’s oxygen from ocean plants in every breath we take. Most of this oxygen comes from tiny ocean plants – called phytoplankton – that live near the water’s surface and drift with the currents. Like all plants, they photosynthesize – that is, they use sunlight and carbon dioxide to make food. A byproduct of photosynthesis is oxygen. Scientists estimate that phytoplankton contribute between 50 to 85 percent of the oxygen in Earth’s atmosphere.

Why is Mars sometimes bright and sometimes faint?

Here is the view from above the solar system in early June 2014.  Earth passed between Mars and the sun in April, and now we are flying ahead of it in the race of the planets.  That's why Mars is fainter now than it was in April 2014.

Here is the view from above the solar system in early June 2014. At the center of these diagrams is the sun (yellow dot). Earth (third orbit) passed between Mars (fourth orbit) and the sun in April 2014. By June, we are flying ahead of it in the race of the planets. That’s why Mars is fainter now than it was in April 2014. Image via Fourmilab.

Mars is the world orbiting the sun one step outward from Earth’s orbit. Earth takes one year to orbit the sun once. Mars takes about two years. The orbits of Earth and Mars are the reason Mars is one of the most fascinating planets to watch in our sky, and they are the reason Mars is sometimes bright and sometimes faint. On April 8, 2014, Earth went between the sun and Mars. That’s why Mars was so bright this past April.

Now Mars is fainter, but it still lovely to behold, and its near the moon on the night of June 6.

The brightness of Mars in our sky depends on where our two planets are in orbit around the sun. Sometimes Earth is close to Mars, and sometimes we are far away.

We are relatively close – and Mars appears at its brightest in our sky for that two-year period – every time Earth passes between the sun and Mars. That’s what’s happening today.