Posts Tagged ‘Ursa Major’

Sparks in the Dark


Violent things can come in small faint packages as shown in this NASA/ESA Hubble Space Telescope image of the starburst galaxy NGC 3738.

Explore the glowing red reservoirs of hydrogen gas, filaments of dust, and diffuse glow of thousands of stars in this faint irregular galaxy. What shapes and stories do you see? Leave a note in the comments below.

NGC 3738 is a dwarf galaxy in the middle of extreme star formation. The glowing red areas are full of hydrogen, the stuff that helps make new stars. Gravity pulls together gas and dust in pockets within the cloud. As the pocket becomes more massive, it begins to heat up until eventually it can become hot enough to fuse hydrogen atoms in a sustainable nuclear reaction. These new stars give off strong stellar winds and ultraviolet radiation that excites hydrogen atoms in the rest of the cloud causing it to glow a characteristic red.

This galaxy is relatively close to Earth; just 12 million light-years from the Sun; meaning light, traveling nearly 6 trillion miles per year, took 12 million years to cross the intergalactic distance. NGC 3738 is a compact bluish dwarf galaxy, the faintest of starburst galaxies. Blue compact dwarfs are generally blue because of large clusters of hot, blue and young stars. These stars tend to be massive, meaning they burn through their supply of hydrogen fuel within just a million years. If they are massive enough, they will end their lives in cataclysmic stellar explosions called supernovae. For a time, a single star can outshine an entire galaxy, releasing more energy in a few moments than our Sun produces in its entire expected lifespan of 8 billion years.

As you explore NGC 3738, you may notice it seems jumbled and disorganized. These galaxies don’t have spiral arms nor bright center bulges. Some astronomers believe these galaxies resemble some of the earliest galaxies that formed in the early Universe and may provide clues into how stars and galaxies formed during that time. As you pan across the image, look for dozens of faint and faraway galaxies scattered throughout this deep image of the cosmos.

NGC 3738, first observed by British astronomer William Herschel in 1789, is found in the constellation Ursa Major, The Great Bear or Big Dipper. It belongs to the Messier 81 group of galaxies, a nearby galactic cluster.

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A Rainbow Tightly Spun

NASA, ESA, CXC, JPL, Caltech and STScI

Tightly spun filaments of color wind around the core of the Pinwheel galaxy in this combo image from four of NASA’s Great Observatories.

Explore the arching tails of color in this image. What stories or pictures do you see? Leave a note in the comments below.

The Pinwheel Galaxy lies fairly close to Earth; just 21 million light-years away toward the constellation Ursa Major, the Great Bear or the Big Dipper. It is considered a grand design spiral galaxy and we see it nearly face-on allowing astronomers a good look at the tight, bright nucleus and long, graceful spiral arms. This galaxy is also about 70 percent larger than our own Milky Way Galaxy. It dwarfs our galaxy with a diameter of 170,000 light-years.

Composite images, images made from several telescopes, like this help astronomers match up features that show brightly in some parts of the light spectrum with those in others. They are more than just a rainbow of pretty colors. Each color tells a different story about how stars form and how they die. Red colors in this image come from the Spitzer Space Telescope. Warm dust, where stars are being born, shine brightly for Spitzer. Yellow bits of starlight shining through are from the Hubble Space Telescope. Hubble sees the Universe as we would see it with our own eyes in visible light. Blue areas shine brightly in ultraviolet. These are young, hot stars seen by NASA’s Galaxy Evolution Explorer, or GALEX, telescope. The Chandra X-ray telescope sees areas in purple. This is light given off by supernovae, exploded stars, hot gas and material falling into black holes.

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Salt and Pepper

ESA/Hubble & NASA

Salt and pepper hang in amorphous star clouds in this image of irregular galaxy DDO 82 from the NASA/ESA Hubble Space Telescope.

Explore the partial spiral structure of DDO 82, also known as UGC 5692. What stories or shapes do you see? Leave a note in the comments below.

Astronomers classify this dwarf galaxy as an Sm galaxy or Magellanic spiral galaxy. This galaxy is similar to the Large Magellanic Cloud, a nearby dwarf galaxy to the Milky Way Galaxy. Both have one spiral arm. And unlike their larger cousins with billions of stars, dwarf galaxies have only a few million stars.

Zoom in close to the blue stars at the center of the image. These blue patches are new stars or star clusters. Red and yellow stars along the outside are older stars. Peppered throughout the background look for faraway galaxies. The bright stars in the image are nearby stars that are part of the Milky Way Galaxy. The green halo near the star in the center is light playing in the optics of the Hubble Space Telescope.

DDO 82 gets its name from its entry number in the David Dunlap Observatory Catalog. Canadian astronomer Sidney van den Bergh compiled this list of dwarf galaxies in 1959. The galaxy is part of the M81 Group, about three dozen galaxies just 13 million light-years toward the constellation Ursa Major, the Great Bear.

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Pink Puffs

Credit: ESA/Hubble & NASA

Pink puffs of cloud created by supernovae explosions dominate this image from NASA’s Hubble Space Telescope.

Explore the glowing bubbles of IC 2574. What stories or patterns do you see? Leave a note below.

IC 2574 is also known as Coddington’s Nebula after American astronomer Edwin Coddington who discovered the galaxy in 1898. The pink shells of gas blown open by the supernovae are surrounded by blue stars. Supernovae explosions send shockwaves throughout the surrounding dust clouds smashing material together. This compression can cause new stars to form. The pink color comes from hydrogen gas that glows because of blistering radiation from the newborn stars.

Astronomers classify IC 2574 as a dwarf irregular galaxy. Instead of a clear structure, like the spiral structure of M51, IC 2574 has no organization. Astronomers study these types of galaxies because they give a hint at the earliest galaxies that formed in the Universe. Faraway in the background, look for the glow of scattered galaxies.

IC 2574 is found about 13 million light-years from Earth toward the constellation Ursa Major, the Great Bear or the Big Dipper. The small galaxy is part of the Messier 81 group of galaxies.

A Giant Among Giants

Credit: NASA, ESA, K. Kuntz (JHU), F. Bresolin (University of Hawaii), J. Trauger (Jet Propulsion Lab), J. Mould (NOAO), Y.-H. Chu (University of Illinois, Urbana), and STScI

Galaxies are among the largest structures in the universe. But some galaxies, such as Messier 101, are giants among smaller giants.

M101, also called the Pinwheel Galaxy, is considered a giant galaxy and is best known example of a “grand design spiral.” Explore the mirrored spiral arms as they curve away from the bright galactic core in this image from NASA‘s Hubble Space Telescope. The face-on spiral galaxy shows us vast regions of star-forming nebulae, brilliant, blue areas of new stars and lanes of dark dust. Thick dust and gas give M101 the fuel it needs to create new stars far into the future. M101 is nearly twice as large as our Milky Way. As you move from one side of this galaxy to the other, you will cross 170,000 light-years. Astronomers estimate that the galaxy contains more than 1 trillion stars. Explore also dozens of distant background galaxies seen in the image.

The Pinwheel Galaxy lies just a stone’s throw away, about 25 million light-years from Earth toward the constellation Ursa Major, the Great Bear. Light that we’re seeing from this galaxy has been traveling for 25 million years to reach our eyes here on Earth. When the light rays left M101, Earth was cooling into a series of ice ages, mammals were flourishing along with many modern birds, and whales were appearing in the oceans along with modern sharks.


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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