Posts by 

Don Machholz

The Bortle survival limit for comets

Astronomers learn even from failed comets. The Bortle survival limit gives us a prediction as to whether a comet will survive perihelion.

Meet M13, the Great Cluster in Hercules

Many stargazers call it the finest globular cluster in the northern half of the heavens. It's M13, also known as the Great Cluster in Hercules.

Asteroid Apophis to sweep close 7 years from now

Apophis' flyby in March 2021 enabled astronomers to conclude there's no chance this asteroid will strike Earth anytime soon. The next flyby will be in 2029.

Yarkovsky effect: Pushing asteroids with sunlight

The Yarkovsky effect is a minuscule push on a small body in space, imparted by nothing more than sunlight. It can change the direction of asteroids.

Cor Caroli, named for the heart of a king

Cor Caroli is a binary star and the brightest star in the northern constellation Canes Venatici, the Hunting Dogs. Its name means Heart of Charles.

Comet Leonard has disintegrated

Comet Leonard, the bright comet of 2021, has disintegrated. Photos show the nucleus and coma have disappeared, leaving nothing but a ghostly streak.

How to find Delta Aquariid radiant point

How to spot the radiant point for the Delta Aquariid meteor shower, going on now. Plus ... why meteors in annual showers have radiant points.