The Local Fluff
24.09.2013

The stars are not alone. In the disk of our Milky Way Galaxy about 10 percent of visible matter is in the form of gas, called the interstellar medium (ISM). The ISM is not uniform, and shows patchiness even near our Sun.

Star Size Comparison 2
12.06.2018

How big is our Sun compared to other stars? In dramatic and popular videos featured on YouTube, the relative sizes of planets, stars, and even the universe are shown from smallest to largest. The featured video begins with Earth's Moon and progresses through increasingly larger moons and planets in our Solar System.

Mercury from Passing BepiColombo
28.06.2022

Which part of the Moon is this? No part -- because this is the planet Mercury. Mercury's old surface is heavily cratered like that of Earth's Moon. Mercury, while only slightly larger than Luna, is much denser and more massive than any Solar System moon because it is made mostly of iron.

Solargraphic Analemmas
2.07.2022

For the northern hemisphere June 21 was the summer solstice, the Sun reaching its northernmost declination for the year. That would put it at the top of each of these three figure-8 curves, or analemmas, as it passed through the daytime sky over the village of Proboszczow, Poland.

Mariner s Mercury
24.11.2001

Mercury, the closest planet to the Sun, remains the most mysterious of the Solar System's inner planets. Hiding in the Sun's glare it is a difficult target for Earth bound observers.

McNaught s Matinee
19.01.2007

Comets grow bright when they're close to the Sun, basking in the intense solar radiation. Of course, they're also usually impossible to see against the overwhelming scattered sunlight. But surprising Comet McNaught...

A Colorful Solar Corona over the Himalayas
11.01.2016

What are those colorful rings around the Sun? A corona visible only to Earth observers in the right place at the right time. Rings like this will sometimes appear when the Sun or Moon is seen through thin clouds.

Eclipse Street, Hong Kong
25.06.2020

On June 21 an annular solar eclipse came soon after the solstice and our fair planet's northernmost sunset for 2020. At maximum eclipse, the New Moon in silhouette created a ring of fire visible along a narrow path at most 85 kilometers wide.

A Solar Corona Ejection
8.11.1996

The Sun would not be a nice place to spend the summer. One reason, besides the extreme heat, is that explosions are common there. In the above picture, magnetic fields buckle releasing previously constrained hot material from the upper atmosphere of the Sun.

Mariner's Mercury
17.12.1996

Mercury, the closest planet to the Sun, remains the most mysterious of the Solar System's inner planets. Hiding in the Sun's glare it is a difficult target for Earth bound observers.