Is the Moon larger when near the horizon? No -- as shown above, the Moon appears to be very nearly the same size no matter its location on the sky. Oddly, the cause or causes for the common Moon Illusion are still being debated. Two leading explanations both hinge on the illusion that foreground objects make a horizon Moon seem farther in the distance. The historically most popular explanation then holds that the mind interprets more distant objects as wider, while a more recent explanation adds that the distance illusion may actually make the eye focus differently. Either way, the angular diameter of the Moon is always about 0.5 degrees. In the above time-lapse sequence of the Moon taken in 2007, with one exposure taken to bring up the foreground of Izmit Bay in Turkey . On the occasion of our 14th anniversary , the APOD editors thank all of our contributors and mirror site operators whose volunteer efforts help bring the wonders of astronomy to millions of people around the world. Additional thanks also go to our Turkish mirror site operators for submitting the above mouseover image.

Dark dust lit by the bright yellow star Antares highlight this photogenic starscape of the southern sky. A wider angle image shows the central band of our Milky Way Galaxy connected to Antares by streams of dust knows as the Dark River . At the head of the Dark River the dust appears in dense knots. One of the densest knots is B44 , pictured near the bottom of the above image. Off to the left of the above image lies Antares, a star so bright that the pictured dust reflects its light, giving it a distinct yellow hue. Light from the blue star on the image left creates a surrounding blue reflection nebula named IC 4605 . B44 and IC 4605 lies about 500 light years distant toward the constellation of the Scorpion .

The center of our Milky Way Galaxy is hidden from the prying eyes of optical telescopes by clouds of obscuring dust and gas. But in this stunning vista , the Spitzer Space Telescope's infrared cameras, penetrate much of the dust revealing the stars of the crowded galactic center region. A mosaic of many smaller snapshots, the detailed, false-color image shows older, cool stars in bluish hues. Reddish glowing dust clouds are associated with young, hot stars in stellar nurseries. The very center of the Milky Way was only recently found capable of forming newborn stars . The galactic center lies some 26,000 light-years away, toward the constellation Sagittarius . At that distance, this picture spans about 900 light-years.

Inspired by the night skies of planet Earth in the International Year of Astronomy , photographer Larry Landolfi created this tantalizing fantasy view. The composited image suggests a luminous Milky Way is the heavenly extension of a country road. Of course, the name for our galaxy, the Milky Way (in Latin, Via Lactea), does refer to its appearance as a milky band or path in the sky. In fact, the word galaxy itself derives from the Greek for milk. Visible on moonless nights from dark sky areas, though not so bright or colorful as in this image, the glowing celestial band is due to the collective light of myriad stars along the plane of our galaxy, too faint to be distinguished individually. The diffuse starlight is cut by dark swaths of obscuring galactic dust clouds. Four hundred years ago, Galileo turned his telescope on the Milky Way and announced it to be "... a congeries of innumerable stars ..."

SNR 0104 is a supernova remnant with an unusual shape. Found 190,000 light-years away in our neighboring galaxy the Small Magellanic Cloud , SNR 0104 is suspected of being the expanding debris cloud from a Type 1a supernova - the catastrophic thermonuclear explosion of a white dwarf star. For example, like Type 1a supernova remnants within our galaxy, investigations show that it contains large amounts of iron. But unlike other Type 1a remnants, including the well-studied Tycho , Kepler , and SN 1006 , SNR 0104 is definitely not spherical. In fact, the remnant's shape suggests this supernova explosion was very asymmetric and produced strong jets. This intriguing composite image combines Chandra Observatory x-ray data of the remnant, shown in purple hues, with Spitzer Space Telescope infrared data covering the wider region, mapped to red and green colors. It indicates that the supernova explosion took place in the complicated and dense environment of a star-forming region . So, an alternative explanation is that the expanding debris cloud is sweeping up clumpy interstellar material, accounting for the odd shape of SNR 0104. The broad, multiwavelength view spans about 1,800 light-years at the estimated distance of SNR 0104.

A sea of clouds laps at rugged moutain peaks of the French Pyrenees in this serene view from Pic du Midi Observatory. The time exposure was recorded on June 4, with the constellations Sagittarius and Scorpius shining in the starry night . At the top right lies a faint, but colorful moondog or paraselene . Analogous to a sundog or parhelion , the paraselene is produced by moonlight shining through thin, hexagonal-shaped ice crystals in high cirrus clouds . As determined by the ice crystal geometry, a bright gibbous Moon illuminates the scene from beyond the picture's right edge, 22 degrees from the lovely paraselene.

These clouds of interstellar dust and gas have blossomed 1,300 light-years away in the fertile star fields of the constellation Cepheus . Sometimes called the Iris Nebula and dutifully cataloged as NGC 7023 , this is not the only nebula in the sky to evoke the imagery of flowers . Surrounding it, obscuring clouds of dust and cold molecular gas are also present and can suggest other convoluted and fantastic shapes. Within the Iris, dusty nebular material surrounds a hot, young star. The dominant color of the brighter reflection nebula is blue, characteristic of dust grains reflecting starlight. Central filaments of the cosmic dust glow with a faint reddish photoluminesence as some dust grains effectively convert the star's invisible ultraviolet radiation to visible red light. Infrared observations indicate that this nebula may contain complex carbon molecules known as PAHs . At the estimated distance of the Iris Nebula this remarkable wide field view is over 30 light-years across.

Across the heart of the Virgo Cluster of Galaxies lies a striking string of galaxies known as Markarian's Chain. The chain, pictured above , is highlighted on the upper right with two large but featureless lenticular galaxies, M84 and M86 . Prominent to their lower left is a pair of interacting galaxies known as The Eyes . The home Virgo Cluster is the nearest cluster of galaxies , contains over 2000 galaxies, and has a noticeable gravitational pull on the galaxies of the Local Group of Galaxies surrounding our Milky Way Galaxy . The center of the Virgo Cluster is located about 70 million light years away toward the constellation of Virgo . At least seven galaxies in the chain appear to move coherently , although others appear to be superposed by chance.

What happens to matter that falls toward an energetic black hole? In the case of Cygnus X-1 , perhaps little of that matter actually makes it in. Infalling gas may first collide not only with itself but with an accretion disk of swirling material surrounding the black hole . The result may be a microquasar that glows across the electromagnetic spectrum and produces powerful jets that expel much of the infalling matter back into the cosmos at near light speed before it can even approach the black hole's event horizon . Confirmation that black hole jets may create expanding shells has come recently from the discovery of shells surrounding Cygnus X-1 . Pictured above on the upper right is one such shell quite possibly created by the jet of microquasar and black hole candidate Cygnus X-1 . Rolling your cursor over the image will bring up an annotated version. The physical processes that create the black hole jets is a topic that continues to be researched.

Orbiting the Sun between Mars and Earth , asteroid 433 Eros was visited by the robot spacecraft NEAR-Shoemaker in 2000 February. High-resolution surface images and measurements made by NEAR 's Laser Rangefinder ( NLR ) have been combined into the above visualization based on the derived 3D model of the tumbling space rock . NEAR allowed scientists to discover that Eros is a single solid body, that its composition is nearly uniform, and that it formed during the early years of our Solar System . Mysteries remain, however, including why some rocks on the surface have disintegrated. On 2001 February 12, the NEAR mission drew to a dramatic close as it was crash landed onto the asteroid's surface , surviving well enough to return an analysis of the composition of the surface regolith . In December of 2002, NASA made an unsuccessful attempt to communicate with the spacecraft after it spent 22 months resting on the asteroid's surface. NEAR will likely remain on the asteroid for billions of years as a monument to human ingenuity at the turn of the third millennium .