The clouds of stellar gas almost jump right out of my screen! It’s a far cry from the view of the nebula that we’re used to, in the bottom image. Phil Plait has a great description of what you’re seeing at Bad Astronomy:
Just off the top of the Hubble picture is the bright star system Sigma Orionis, composed of five incredibly luminous stars. Combined, they shine with the power of over 75,000 Suns! They are responsible for heating and exciting the gas behind the Horsehead.
The Horsehead itself is the site of ongoing star formation. The dense gas and dust inside the nebula is collapsing to form stars, and, at the same time, the edges are being eroded away by the fierce ultraviolet light of Sigma Orionis. The top of the Horsehead is acting a bit like a shield, protecting the material beneath it, which is why it’s taken on that umbrella-like shape. You can see more sculpted pillars of material around the sides, too, like sandbars in a stream.
Well done, Hubble team. Keep up the good work. You’ve inspired millions.
This is an image of the Orion Molecular Cloud Complex including the Flame nebula and the famous Horsehead nebula as seen from from NASA’s Spitzer Space Telescope. The Horsehead is only one small feature in the Orion Molecular Cloud Complex, dominated in the center of this view by the brilliant Flame nebula (NGC 2024). The smaller, glowing cavity falling between the Flame nebula and the Horsehead is called NGC 2023. These regions are about 1,200 light-years away.
In this infrared image from Spitzer, blue represents light emitted at a wavelength of 3.6-microns, and cyan (blue-green) represents 4.5-microns, both of which come mainly from hot stars. Green represents 8-micron light and red represents 24-micron light. Relatively cooler objects, such as the dust of the nebulae, appear green and red.
Rising from a sea of dust and gas, the legendary Horsehead Nebula emerges. This amazing NASA’s Hubble Space Telescope close-up reveals the cloud’s intricate structure. Also known as Barnard 33, the Horsehead is a cold, dark cloud of gas and dust, silhouetted against the bright nebula, IC 434. The bright area at the top left edge is a young star still embedded in its nursery of gas and dust. The top of the nebula also is being sculpted by radiation from a massive star located out of view.
Image Credit: NASA, NOAO, ESA and The Hubble Heritage Team (STScI/AURA)
The Horsehead Nebula, also known as Barnard 33 is part of the much larger Orion Molecular Cloud Complex. Due to its recognizable shape — which roughly resembles the head and neck of a horse, it is one of the most well known astronomical objects. The nebula is, in fact, an extremely dense dark cloud projecting in front of the bright emission nebulaIC434.
Credit: NASA, ESA, and the Hubble Heritage Team (AURA/STScI); ESO