Planets Around Sun-Like Stars
31.01.1996

Do many Sun-like stars have planets? Speculation on this point has been ongoing since humanity's realization that other stars existed. Only in the past year, however, have answers and discoveries been realized. The above plot summarizes the four known cases of normal stars having planets.

The Millennium that Defines Universe
1.01.2000

Welcome to the millennial year at the threshold of millennium three. During millennium two, humanity continually redefined its concept of "Universe": first as spheres centered on the Earth, in mid-millennium as the Solar System, a few centuries ago as the Galaxy, and within the last century as the matter emanating from the Big Bang.

Jets from the Necklace Nebula
18.05.2021

What celestial body wears the Necklace Nebula? First, analyses indicate that the Necklace is a planetary nebula, a gas cloud emitted by a star toward the end of its life. Also, what appears to be diamonds in the Necklace are actually bright knots of glowing gas.

APOD: 2024 August 7 Б Milky Way Behind Three Merlons
7.08.2024

To some, they look like battlements, here protecting us against the center of the Milky Way. The Three Merlons, also called the Three Peaks of Lavaredo, stand tall today because they are made of dense dolomite rock which has better resisted erosion than surrounding softer rock.

Spherical Planetary Nebula Abell 39
28.07.2005

Ghostly in appearance, Abell 39 is a remarkably simple, spherical nebula about five light-years across. Well within our own Milky Way galaxy, the cosmic sphere is roughly 7,000 light-years distant toward the constellation Hercules.

Venus: Earth's Sister Planet
15.08.1995

This picture in visible light was taken by the Galileo spacecraft. Venus is very similar to Earth in size and mass - and so is sometimes referred to as Earth's sister planet - but Venus has a quite different climate.

A Quintet of Galaxies
15.11.1995

Five closely grouped galaxies are visible in this image made using the Kitt Peak National Observatory 2.1 meter telescope. The grouping is commonly known as Stephan's Quintet. Four of the galaxies show essentially the same redshift suggesting that they are at the same distance from us.

Apollo 15: Driving on the Moon
23.02.1996

Apollo 15 astronaut James Irwin works on the first Lunar Roving Vehicle, before he and fellow astronaut David Scott take it out for a drive. Sloping up behind the lunar module "Falcon" on the left are lunar mountains Hadley Delta and Apennine Front, while about 5 kilometers behind Irwin is St. George Crater.

On the Possibility of Ascending to Mars
19.10.2005

On another October 19, in 1899, a 17 year-old Robert Goddard climbed a cherry tree on a beautiful autumn afternoon in Worcester, Massachusetts. Inspired by H.G. Wells' War of the Worlds and gazing...

A Waterspout in Florida
17.05.2020

What's happening over the water? Pictured here is one of the better images yet recorded of a waterspout, a type of tornado that occurs over water. Waterspouts are spinning columns of rising moist air that typically form over warm water.