Category: Eyes in the Sky

A Bubble of Many Colors

Credit: X-ray: NASA/CXC/SAO; Optical: NASA/STScI; Infrared: NASA/JPL-Caltech/Steward/O.Krause et al.


Supernova remnant Cassiopeia A glows with many colors in this composite image from NASA’s Great Observatories.

Zoom into the jumbled strands of colors. What stories or pictures do you see? Leave a note below.

Cassiopeia A, or Cas A, is the remnant of a star that exploded. Supernovae are the ultimate end of stars that are about ten times more massive than our Sun. When stars this big run out of hydrogen fuel, they quickly expand. Their great gravity however pulls the material back in toward the star where it heats up very fast creating a runaway nuclear fusion reaction. The star becomes unstable and explodes.

As you explore the image, look for the different colors offered by images of each observatory. Astronomers used to think that the explosion scattered material evenly around the star. But knots and filaments show that material was ejected at different times and speeds. Spitzer imagery shows reddish warm dust in the outer shell of the supernova with a comfortable temperature of about 80 degrees Fahrenheit (10 degrees Celsius). Hubble Space Telescope imagery shows a fine yellow filament structure of warmer gases. Chandra imagery shows superhot gas in blues and greens. The hot gas was created when material ejected at high speed during the explosion slammed into the calm gas and dust surrounding the star. Look for the turquoise dot near the center of the image. This may be the neutron star created during the supernova. A neutron star is the hot and super-dense core of an exploded star. Some scientists believe that a black hole resides at the center of the remnant.

Cas A lies about 11,000 light-years from the Earth toward the constellation Cassiopeia. Astronomers believe first light from the supernova reached Earth about 300 years ago. But no one on Earth seems to have seen it. Historians think that John Flamsteed may have noticed the star in 1680. Astronomers theorize that the massive star had ejected a dense bubble of dust that blocked light from the explosion. Scientists discovered the supernova in the 1940s because it is one of the brightest radio sources in the sky. No supernovae have been visible in the Milky Way since.

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Running Starman

Credit: ESA/Hubble and NASA


A runner zooms out of a the swirling mass known as NGC 1483 in this image from the NASA/ESA Hubble Space Telescope.

Explore the blue spiral arms and golden center of this barred spiral galaxy. What stories or shapes do you see? Leave a note below.

NGC 1483 is a nebulous galaxy. Instead of dark dust lanes, this galaxy has haze of stars. Zoom into the blue areas at the leading edges of the spiral arms. Gas and dust gets pushed together creating perfect places for stars to form. The blue stars are usually hot new stars. Older, redder and yellow stars make up most of the galaxy’s central bar. It’s this distinctive thick bar of stars that gives barred spirals their name. About two-thirds of the galaxies astronomers view are barred spirals, including our own Milky Way Galaxy.

Deeper in the image, look for more distant galaxies.

NGC 1483 is found fairly close to Earth at just 40 million light-years. It has taken light traveling 6 trillion miles per year about 40 million years to our telescopes on Earth. That may seem like a great distance. It is but the Universe stretches far beyond to about 13.5 billion light-years. NGC 1483 is part of a loose group of galaxies found toward the southern constellation of Dorado, or dolphinfish in Spanish.

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A Look at the Center

Credit: NASA/CXC/MIT/F.K. Baganoff et al./h6>

A supermassive black hole and other mysteries lie in the center of our galaxy in this image from NASA‘s Chandra X-ray Observatory.

Explore the mysterious filaments, supernova remnants and loops of gas in this image. What shapes or stories do you see? Leave a note below.

For a long time, astronomers have known that a black hole lurks at the center of our Milky Way Galaxy. They call it Sagittarius A* or SgrA* for short. The galactic center is far away. If you look to the south in the northern hemisphere summer toward the bottom and brightest part of the Milky Way, you can see toward the center of our galaxy. Light from the galactic core, traveling more than 6 trillion miles a year, takes about 26,000 years to reach our eyes on Earth. Lots of stars and thick veils of gas and dust block our view from Earth. Scientists see the black hole using X-ray images like this one and other infrared images. The X-ray light picked up from the sensors on the Chandra Observatory are high-energy particles created as matter spun into the black hole. Massive young stars near the black hole provide the gas that the black hole consumes.

Chandra looked at the center of the galaxy for about one million seconds, almost two weeks, to create this deep image. This gave astronomers a good view of the lobes of hot gas arcing light years on either side of the black hole. The image also shows scientists a good view of a supernova remnant called Sgr A East. Look close and you can see faint filaments of hot gas. Astronomers call these pulsar wind nebulae. They may be associated with the strong magnetic fields created by the fast spinning neutron stars.

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Striking Starry Eye

Credit: ESO


trands of cold gas and dust stream from the center of this striking image of the Helix Nebula from the European Southern Observatory.

Explore the clumps and rings of this nearby planetary nebula. What patterns or stories do you see? Fireworks? A flower? Leave a note below.

The Helix Nebula formed when a star much like our Sun reached the final stages of life. After billions of years, the star ran out of hydrogen fuel. In an attempt to keep burning the remaining fuel, the star ballooned in size to become a red giant. But even this is not enough. The star puffed its outer layers into space forming an expanding bubble. A tiny blue dot, a white dwarf, is all that remains of the star. This white-hot cinder will take billions of years to cool.

From side to side, the Helix Nebula spans about four light-years; about the same distance between our Sun and the nearest star. Blazing radiation from the dead core of the star cause the gas in the expanding rings to glow like a neon sign. Zoom in close into the strands pointing toward the center of the system. Astronomers call these cometary knots. Each of these knots is about the size of our solar system. Scientists don’t know why the knots form but they do know how. Clumps of gas and dust blown outward from the star by the strong solar wind clump together. The leading edge of the knots shields the rest of the clump from the solar wind and radiation that would blow them away.

The image was taken with ESO’s VISTA telescope at the Paranal Observatory high in the mountains of Chile. The clear skies make it easy for the 4.1-meter telescope to pick out the faint light from the nebula and from faraway galaxies. Although the gas in this nebula is cool, VISTA’s infrared sensors detect the faint heat from the expanding cloud. The nebula looks much different to our eyes in visible light.

The Helix Nebula is one of the closest planetary nebulae to Earth. Light from the nebula has traveled at 6 trillion miles per year for 700 years to reach our eyes on Earth. It is found in the constellation Aquarius, the Water Bearer.

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Cosmic Horseshoe

Credit: NASA/ESA Hubble

A blue cosmic horseshoe rings a massive galaxy in this image from the NASA/ESA Hubble Space Telescope.

Explore the Cosmic Horseshoe and the faraway galaxies in this image of deep space. What stories or pictures do you see? Leave a note below.

The Cosmic Horseshoe is an example of an Einstein Ring. Albert Einstein predicted that gravity could bend light. The ring is actually a galaxy on the far side of the bright galaxy at its center. The center galaxy has incredible mass; about ten times that of our own Milky Way. It is one of a group of galaxies known as Luminous Red Galaxies. The strong gravitational pull of the galaxy warps and magnifies the light of the faraway galaxy like a lens.

The chance alignment offers scientists a glimpse at the early Universe. By studying the light of the blue galaxy, astronomers believe light from the galaxy has been traveling to our eyes for almost 11 billion years. The Universe itself is believed to be incredibly old at about 13.7 billion years old.

Astronomers discovered the Cosmic Horseshoe in 2007.


The ancient peoples saw pictures in the sky. From those patterns in the heavens, ancient storytellers created legends about heroes, maidens, dragons, bears, centaurs, dogs and mythical creatures...
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