A Green Flash from the Sun
4.06.2014

Many think it is just a myth. Others think it is true but its cause isn't known. Adventurers pride themselves on having seen it. It's a green flash from the Sun. The truth is the green flash does exist and its cause is well understood.

A Triangular Shadow of a Large Volcano
5.07.2011

Why does the shadow of this volcano look like a triangle? The Mount Teide volcano itself does not have the strictly pyramidal shape that its geometric shadow might suggest. The triangle shadow phenomena is not unique to the Mt. Teide, though, and is commonly seen from the tops of other large mountains and volcanoes.

A Triangular Shadow of a Large Volcano
9.06.2019

Why does the shadow of this volcano look like a triangle? The Mount Teide volcano itself does not have the strictly pyramidal shape that its geometric shadow might suggest. The triangle shadow phenomena is not unique to the Mt. Teide, though, and is commonly seen from the tops of other large mountains and volcanoes.

Comet Catalina Emerges
7.12.2015

Comet Catalina is ready for its close-up. The giant snowball from the outer Solar System, known formally as C/2013 US10 (Catalina), rounded the Sun last month and is now headed for its closest approach to Earth in January.

Comet PanSTARRS and the Helix Nebula
5.06.2016

It's rare that such different objects are imaged so close together. Such an occasion is occurring now, though, and was captured two days ago in combined parallel exposures from the Canary Islands of Spain.

Moonrise and Mountain Shadow
14.03.2020

What phase of the Moon is 3.14 radians from the Sun? The Full Moon, of course. Even though the Moon might look full for several days, the Moon is truly at its full phase when it is 3.14 radians (aka 180 degrees) from the Sun in ecliptic longitude.

The Eagle Nebula in Hydrogen Oxygen, and Silicon
27.02.2008

Bright blue stars are still forming in the dark pillars of the Eagle Nebula. Made famous by a picture from the Hubble Space Telescope in 1995, the Eagle Nebula shows the dramatic process of star formation.

Orions Belt and Sword over Teides Peak
28.03.2016

The southern part of Orion, the famous constellation and mythical hunter, appears quite picturesque posing here over a famous volcano. Located in the Canary Islands off the northwest coast of Africa, the snow-peaked Teide is one of the largest volcanoes on Earth.

Comet LINEAR: Fade To Black
13.09.2000

Only last month the stage was set for Comet LINEAR (C/1999S4 LINEAR) to become the first "naked-eye" comet of Y2K. It didn't fill that role, of course, but it did turn in a very dramatic performance.

Green Flash at Moonrise
5.06.2015

Follow a sunset on a clear day against a distant horizon and you might glimpse a green flash just as the Sun disappears, the sunlight briefly refracted over a long sight-line through atmospheric layers. You can spot a green flash at sunrise too.