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Why aren’t there eclipses at every full and new moon?

Photo credit: pizzodisevo

A solar eclipse happens at the new moon – when the moon passes between the sun and Earth. A lunar eclipse happens when the Earth, sun and moon align in space, with Earth in the middle. Why aren’t there eclipses at every full and new moon?

Signs of spring! Have a look …

“The glory of spring!” Photo: Gledra Kregzdys

No matter what the weather where you are, enjoy these photos from EarthSky friends on Facebook and G+.

Star of the week: Mimosa second-brightest in Southern Cross

Constellation Crux photo by Christopher J Picking in New Zealand. Mimosa is the second-brightest star in the Cross, on the left in this image. More information about this photo here. Used with permission

So far to the south as to be unfamiliar to the ancient Greeks and Romans, this star does not have a classical name. It is Beta Crucis, the second star of the Southern Cross.

What’s the birthstone for April?

Photo credit: Kim Alianz

Photo credit: Kim Alianz

Happy birthday April babies! Your birthstone, the diamond, is the rich cousin of graphite.

Moon at apogee – farthest point – on April 1


No April Fools! The moon swings out to apogee – the moon’s farthest point from Earth in its orbit – twice in one month: April 1 and 29. We list the dates for this year’s 13 apogees and 13 perigees.

Spring means these 4 hibernators are waking up

Black bear. Image Credit: U.S. Fish and Wildlife Service.

Black bear. Image Credit: U.S. Fish and Wildlife Service.

With the onset of spring in the Northern Hemisphere, animals that hibernate are waking up from a long-period of deep sleep. They spent the winter hibernating to conserve energy when food was scarce.

Eclipsed moon and sun together this Saturday?

Tonight's sunset and moonrise - September 19, 2013 - as seen by EarthSky Facebook friend Andy Somers in Noumea, New Caledonia.  One of the characteristics of the Harvest Moon is that it rises around the time of sunset for several evenings in a row.  Thank you, Andy.

This photo does not show an eclipsed moon, but it does show a simultaneous sunset and (nearly) full moonrise as captured by EarthSky Facebook friend Andy Somers in Noumea, New Caledonia in September 2013. On Saturday, April 4, 2015 – from just the right spot on Earth – you might see something like this … but the moon will be in eclipse!

If you’re in just the right spot on Earth, you might observe the eclipsed moon setting while the sun rises – or the eclipsed moon rising while the sun sets – on Saturday, April 4. This is called a selenelion. Celestial geometry says should not happen, but it does happen. We tell you why – and provide a chart of who will see the selenelion on Saturday – inside.

Follow Big Dipper’s arc to Arcturus

Use the Big Dipper to arc to Arcturus.

Use the Big Dipper to arc to Arcturus.

Tonight … learn and use the most useful star mnemonic you’ll ever encounter. It’s … follow the arc to Arcturus and drive a spike to Spica. Scouts learn this phrase. Grandparents teach it to kids. Arcturus and Spica are so bright that you can often see them on a moonlit night – like tonight. Follow the links inside to learn more.

April 2015 guide to the five visible planets

Skywatcher, by Predrag Agatonovic.

Skywatcher, by Predrag Agatonovic.

Three planets easy to see throughout April 2015. Venus and Jupiter at nightfall. Saturn late evening on. Mercury joins in mid-month for its best northern apparition of the year in the evening sky.

Auroras in motion

Northern Lights from Sergio Garcia Rill on Vimeo.

Take 3 minutes to watch this green and ghostly time-lapse video of the Alaskan northern lights. It was made from 4,450 photos by our friend Sergio Garcia Rill