On Saturday and Sunday nights, Dec. 15 and 16, Bob expects Comet Wirtanen to achieve naked-eye visibility – the first...

Comet Wirtanen will soon pay Earth its closest-ever visit. It should be large and blobby-looking, appearing as a fuzzy glob...

The Martian surface air is 30 times thinner than the air atop Mount Everest. And if that weren’t bad enough,...

By day the antisolar point is marked by the shadow of your head. At night it’s the most happening place...

Here are my top six sky apparitions that belong on everyone’s bucket list, most of which appear in your own...

One word is so consistently mispronounced that I’ve been repeatedly corrected when I say it the right way, which is...

You go there when you want privacy. Lagrangian points are very cool. So why haven’t we ever explored them in...

How can such an intangible thing as the fact of awareness, such as experiencing the smell of buttered corn, arise...

Friday-Saturday, Sept. 14-15: There’s probably a supermassive black hole in the core of every galaxy. Ours has the weight of...

Summer offers a profusion of ice-crystal phenomena.

A rainbow requires a sunshower. It must be raining. But the CZA can appear against a blue sky.

Saturday-Sunday, August 11-12: It’s all due to a backwards comet. All we need are mostly clear skies.

Want to see it for yourself? It’s easy, if you can get to a place with an unobstructed sweep of...

Friday night, July 27: That’s when the Sun, the Earth and the planet Mars form a straight line in space. Mars rises...

Dewpoints in the 40s and 50s mean dry air, low 60s mean medium-dry air, high 60s and 70s indicate steamy...

During the next three months, from now through September, Venus will visibly shift to the left. Each evening at nightfall,...

We always assume aliens would know about circles and pi, and realize that hydrogen is the element that dominates the...

Here’s how to determine Earth’s shape without trusting the government, astronaut testimony or spacecraft images.

The night’s brightest object is the Moon, of course. But the second-brightest? Surprisingly, most people don’t know. That’s why a...

Earth’s climate gets cooler when there are fewer solar storms. An extreme example happened between 1645 and 1715, when the...