NGC 2022


NGC 2022 is a planetary nebula in the constellation Orion. In early telescopes (and in today’s medium-sized amateur telescopes) such nebulae look like small grayish patches of light. Since they don’t look like stars, but a bit like the gas giant planets, early astronomers tagged them as “planetary nebula,” and the name has stuck.

When stars like the Sun grow old, they expand into red giants. They then begin to lose their outer layers into space, forming a shell of gas. As the evolving star’s core shrinks and grows hotter, it emits ultraviolet light that causes the expelled gases to glow.

Image Credit: NASA / ESA

Orion in 3D


This animation begins with a pan across the sky to Orion, and the lines of the 2D stick figure constellation are drawn in. As the point of view slowly begins to circle around the centroid of the stars, the stick figure quickly “distorts” into a  3D structure. The viewpoint backs up to keep the entire figure onscreen as it move through a complete circle. At the end of the circle, the camera zooms to finish at the location of the Earth/Sun (to avoid an obvious distraction, the Sun is not included in the visualization).

During the final zoom in, notice how Sirius grows in apparent brightness (bottom of frame, just left of center). While Sirius is the brightest star in our night sky, a major contribution of its apparent brightness comes from its proximity to the Sun.

Video Credit: NASA

Mintaka, Alnilam, and Alnitak


orion_arisingThose are the names of the stars in Orion’s belt, and they can be seen peeking through Earth’s atmosphere in this picture made from the International Space Station by astronaut Reid Wiseman. Orion’s sword, home to the great Orion Nebula, hangs above his belt in an orientation opposite to what those of us who live in the northern hemisphere are used to. Rigel, at the foot of Orion, is still higher above Orion’s belt. Sirius, alpha star of the constellation Canis Major, is to the right of center in the frame. That’s the station’s Destiny Laboratory module is in the foreground at the top right.

Image Credit: NASA

Orion in 3D


This animation begins with a pan across the sky to Orion, and the lines of the 2D stick figure constellation are drawn in. As the point of view slowly begins to circle around the centroid of the stars, the stick figure quickly “distorts” into a  3D structure. The viewpoint backs up to keep the entire figure onscreen as it move through a complete circle. At the end of the circle, the camera zooms to finish at the location of the Earth/Sun (to avoid an obvious distraction, the Sun is not included in the visualization).

During the final zoom in, notice how Sirius grows in apparent brightness (bottom of frame, just left of center). While Sirius is the brightest star in our night sky, a major contribution of its apparent brightness comes from its proximity to the Sun.

Video Credit: NASA

Witch Head Nebula


Witch Head NebulaThis reflection nebula does look a bit like a fairytale crone. The Witch Head Nebula (aka IC 2118) is in the constellation Orion near the star Rigel. It glows because of light reflected from the star. The color of this very blue nebula is partially caused by blue color of its star. The bluish hue is enhanced because the dust grains reflect blue light more efficiently than red. A similar physical process causes Earth’s daytime sky to appear blue.

Trick or treat.

Image Credit: NASA

A Cosmic Closeup


LLOri_hubble_960This close-up of cosmic clouds blown about by stellar winds features LL Orionis, interacting with the Orion Nebula. LL Orionis is a variable star in Orion’s stellar nursery and still in its formative years. It produces a wind more energetic than the wind from our own middle-aged Sun. As the stellar wind runs into slow moving gas, a shock front is formed, similar to the bow wave of a boat moving through water. The small, arcing, graceful structure just above and left of center is LL Ori‘s cosmic bow shock. It’s about half a light-year across. The slower gas is flowing away from the Orion Nebula’s hot central star cluster, the Trapezium is out of the frame of this picture toward the upper left. LL Ori‘s wrap-around shock front is shaped like a bowl that appears brightest when viewed along the “bottom” edge.

Image Credit: NASA, Hubble Legacy Archive

Spitzer’s Orion


orion_spitzerThe Orion Nebula is an immense stellar nursery around 1,500 light-years away. This infrared image from the Spitzer Space Telescope was constructed from data intended to monitor the brightness of the nebula’s young stars, many still surrounded by dusty, planet-forming disks. It covers an area roughly 40 light-years across. Orion’s young stars are only about 1 million years old. (Our Sun’s been around for 4.6 billion years.) The hottest stars are found in the Trapezium Cluster, the brightest cluster near picture center. Spitzer’s liquid helium coolant for it’s most sensitive detectors ran out in May, 2009, so this false color view is from two channels that still remain sensitive to infrared light at warmer operating temperatures.

Image Credit—NASA

At the Heart of Orion


Just below and right of center in this picture of the heart of the Orion Nebula are four hot, massive stars known as the Trapezium. Clustered within a region only about 1.5 light-years in radius, they dominate the core of the dense Orion Nebula Star Cluster. Ultraviolet ionizing radiation from these stars powers the complex star forming region’s visible glow. The Orion Nebula Cluster is about 3 million years old. It was even more compact in its younger years, and a recent theoretical study suggests that runaway stellar collisions during its earlier years may have formed a black hole with more than 100 times the mass of the Sun. A black hole within the cluster could explain the observed high velocities of the Trapezium stars. The Orion Nebula is about 1500 light-years from Earth. If it has a black hole, it would be the closest known black hole to Earth.

Image Credit: NASA