Eskimo Nebula
The Eskimo Nebula (NGC 2392), also known as the Clownface Nebula, was discovered by astronomer William Herschel in 1787. From the ground, it resembles a person's head surrounded by a parka hood. In 2000, the Hubble Space Telescope produced this image of it. From space, the nebula displays gas clouds so complex that they are not fully understood.
The Eskimo Nebula is clearly a planetary nebula. It is surrounded by gas that composed the outer layers of a Sun-like star only 10,000 years ago. The visible inner filaments are ejected by strong wind of particles from the central star. The outer disk contains unusual light-year long orange filaments. NGC 2392 lies about 5000 light-years away and is visible with a small telescope in the constellation of Gemini.
Pillars of Creation
This Hubble image, showing star forming pillars in the Eagle Nebula, is one of the most popular poster images of outer space, and often appears in science-fiction movies. The Eagle Nebula was one of the space regions passed through during the opening "zoom out" shot of the movie Contact (1997), and appeared in the opening scene of the Babylon 5 episode Into The Fire. The Eagle Nebula, along with the Hourglass Nebula, was featured in the liner notes of Pearl Jam's 2000 album Binaural.
Pale Blue Dot
"Pale Blue Dot" is the name of THIS famous Voyager 1 photograph of Earth, and the title of a book by Carl Sagan inspired by the photo. On February 14, 1990, NASA commanded the Voyager 1 spacecraft, having completed its primary mission, to turn around to photograph the planets it had visited. NASA ultimately compiled 60 images from this unique event into a mosaic of the Solar System. One image Voyager returned was of Earth, 4 billion miles distant, showing up as a "pale blue dot" in the grainy photo. Britt describes the distance as "more than 4 billion miles". The picture was taken using a narrow-angle camera at 32ยบ above the ecliptic, and created using blue, green, and violet filters. Narrow-angle cameras, as opposed to wide-angle cameras, are equipped to photograph specific details in an area of interest. In addition, only 0.12 pixels represents Earth in the photo.
Sagan said the famous Earthrise picture taking during the Apollo 8 mission, showing the entire Earth above the moon, forced humans to step back and see the Earth as just a part of the universe. In the spirit of that realization, Sagan said he pushed for Voyager to take a photo of the Earth from its vantage point on the edge of the solar system.
There was danger to the spacecraft's optics from the nearby Sun. Voyager took similar pictures of Venus, Jupiter, Saturn, Uranus and Neptune. Thus the Pale Blue Dot photo was part of a "portait" of the Solar System that was created by Voyager 1.
Supernova 1987A
SN 1987A was a supernova in the outskirts of the Tarantula Nebula in the Large Magellanic Cloud, a nearby dwarf galaxy. It occurred approximately 51.4 kiloparsecs from Earth, close enough that it was visible to the naked eye. It was the closest supernova since SN 1604, which occurred in the Milky Way itself. The light from the supernova reached Earth on February 23, 1987. As the first supernova discovered in 1987, it was labeled "1987A". Its brightness peaked in May with an apparent magnitude of about 3 and slowly declined in the following months. It was the first opportunity for modern astronomers to see a supernova up close.
Since 51.4 kiloparsecs is approximately 168,000 light-years, the cosmic event itself happened approximately 168,000 years ago. To put this in perspective, Homo sapiens sapiens (modern humans) evolved about 200,000 years ago.
Antennae Galaxies
Hubble produced this image in October 1997. The Antennae Galaxies (also known as NGC 4038/NGC 4039) are a pair of galaxies about 68 million ly away in the constellation Corvus. They were both discovered by Friedrich Wilhelm Herschel in 1785.
The chaotic swirls of blues and oranges represent a firestorm of new star birth ignited by the head-on collision of interstellar hydrogen. The long arcing insect-like "antennae" represent matter flung from the scene of the accident.
Hubble Deep Field
The Hubble Deep Field (HDF) is an image of a small region in the constellation Ursa Major, based on the results of a series of observations by the Hubble Space Telescope. It covers an area 144 arcseconds across, equivalent in angular size to a tennis ball at a distance of 100 metres. The image was assembled from 342 separate exposures taken with the Space Telescope's Wide Field and Planetary Camera 2 over ten consecutive days between December 18 and December 28, 1995.
The field is so small that only a few foreground stars in the Milky Way lie within it; thus, almost all of the 3,000 objects in the image are galaxies, some of which are among the youngest and most distant known. By revealing such large numbers of very young galaxies, the HDF has become a landmark image in the study of the early universe, and it has been the source of almost 400 scientific papers since it was created.
Crab Nebula
The Crab Nebula (catalogue designations M1, NGC 1952, Taurus A) is a supernova remnant in the constellation of Taurus. The nebula was first observed in 1731 by John Bevis. It is the remnant of a supernova that was recorded by Chinese and Arab astronomers in 1054. Located at a distance of about 6,300 light years (2 kpc) from Earth, the nebula has a diameter of 11 ly (3.4 pc) and is expanding at a rate of about 1,500 kilometres per second.
The nebula contains a pulsar in its centre which rotates thirty times per second, emitting pulses of radiation from gamma rays to radio waves. The nebula was the first astronomical object identified with a historical supernova explosion.
Cat's Eye Nebula
The Cat's Eye Nebula (NGC 6543) is a planetary nebula in the constellation of Draco. Structurally, it is one of the most complex nebulae known, with high-resolution Hubble Space Telescope observations revealing remarkable structures such as knots, jets and sinewy arc-like features. It was discovered by William Herschel on February 15, 1786, and was the first planetary nebula whose spectrum was investigated, by the English amateur astronomer William Huggins in 1864.
Modern studies reveal several mysteries. The intricacy of the structure may be caused in part by material ejected from a binary central star, but as yet, there is no direct evidence that the central star has a companion. Also, measurements of chemical abundances reveal a large discrepancy between measurements done by two different methods, the cause of which is uncertain.
Gamma Ray Explosion
The Hubble Space Telescope captured this image of a gamma ray explosion [shown at two different scales] on January 23, 1999. At the time it was the most powerful explosion ever recorded.
According to NASA, gammaray bursts "may represent the most powerful explosions in the universe since the Big Bang, the explosive birth of our universe. Hubble images showed that these brief flashes of radiation come from far-flung galaxies that are forming stars at enormously high rates. By pinpointing the host galaxies, Hubble also identified the sources of the 'bursts': the collapse of massive stars."
Protoplanetary Disks
A Hubble Space Telescope image shows "proplyds," or protoplanetary disks, in the Orion Nebula.
According to NASA, nebulae, flattened disks of gas and dust, "are the likely birthplaces of new planetary systems. Hubble provided visual proof that pancake-shaped dust disks around young stars are common, suggesting that the building blocks for planet formation are in place."
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