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Larry Sessions

Larry Sessions

Larry Sessions has written many favorite posts in EarthSky's Tonight area. He's a former planetarium director in Little Rock, Fort Worth and Denver and an adjunct faculty member at Metropolitan State University of Denver. He's a longtime member of NASA's Solar System Ambassadors program. His articles have appeared in numerous publications including Space.com, Sky & Telescope, Astronomy and Rolling Stone. His small book on world star lore, Constellations, was published by Running Press.

What appears to be a densely populated star field with a few galaxies visible.

The Coma Cluster of galaxies

Posted by in Clusters Nebulae Galaxies | 1 hour ago
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The Coma Cluster is one of the richest galaxy clusters known. How many suns and how many worlds might be located in this direction of space?

Observatory dome in foreground, Milky Way in background, and Alpha Centauri's position marked.

Alpha Centauri, star system closest to our sun

Posted by in Astronomy Essentials | Brightest Stars | 4 days ago
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We see this nearly star system as a single star in our sky, but it’s really 3 stars. Of the 3, Proxima is closer to our sun than any other known star.

Alpha and Beta Centauri, pointing to Crux.

Beta Centauri is a Southern Pointer Star

Posted by in Astronomy Essentials | Brightest Stars | 4 days ago
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Beta Centauri – aka Hadar – joins Alpha Centauri in pointing to the Southern Cross. Like Alpha, Beta Centauri is also 3 stars, but 2 of Beta’s stars will someday become nearby supernovae.
Chart showing moon, Castor, Pollux, Procyon on April 12, 2019.

Moon and Gemini stars on April 12

Posted by in Tonight | 1 week ago
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Watch for Gemini’s 2 brightest stars – Castor and Pollux – near tonight’s moon. On the other side of the moon, you’ll see a 3rd bright star. It’s Procyon in the constellation Canis Minor, the Lesser Dog.

Leo loses his tail. We gain a constellation

Posted by in Tonight | 2 weeks ago
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The constellation Leo once had a tail, a clump of faint stars. Now these same stars are known as Coma Berenices, the hair of a queen.

Acrux, brightest star in Southern Cross

Posted by in Brightest Stars | 4 weeks ago
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You have to go far south on Earth’s globe to see the Southern Cross. Bluish Acrux, aka Alpha Crucis, is its brightest star.

Canopus: Sky’s 2nd-brightest star

Posted by and in Astronomy Essentials | Brightest Stars | 2 months ago
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Canopus is the 2nd-brightest star in the sky, and it’s easy to spot on February evenings, if …

Quietly, Regulus ushers in springtime

Posted by in Brightest Stars | 2 months ago
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Regulus, brightest star in Leo the Lion, is now rising in the east after sunset. You might not notice it, but stargazers know that, when Regulus appears in this way, spring is near.

First quarter moon on February 12

Posted by in Tonight | 2 months ago
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The side of the moon we see from Earth appears 50% illuminated tonight. For all of Earth, the moon rises around midday and sets around midnight. Plus the moon’s lighted side points right at Mars tonight!

Will star Betelgeuse explode?

Posted by in Astronomy Essentials | Brightest Stars | 3 months ago
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Yes, it will. The star Betelgeuse will run out of fuel, collapse under its own weight, and then rebound in a spectacular supernova explosion. Someday … but probably not soon.