It is approximately light-years away from Earth. That means even if you could travel at the speed of light, it would still take you years to get there! This image might look like a creepy eyeball, but it's actually a nebula! Astronomers use very powerful telescopes to take pictures of faraway nebulae. What Is a Nebula? The Short Answer:. Cooler, lighter stars like our sun take 10 billion years to become red giants.
This fact actually provides a way of testing how old a group of stars is - jut make an H-R diagram for the stars, and see which classes of stars have evolved off the main sequence! Eventually, all the helium in the core of the star is used up. At this point, what happens next depends on the mass of the star. The heaviest stars, over six to eight times as massive as our sun, have enough pressure in their cores to start fusing carbon.
Once carbon is gone, they explode as supernovae, leaving behind neutron stars or a black holes. Less massive stars simply burn out, shedding their outer layers into beautiful planetary nebulae, and leaving the core as a hot white dwarf.
White dwarfs lie in the lower left corner of the H-R diagram, a cosmic burial ground for dead stars. An H-R diagram showing the evolutionary track of a sun-like star. Nebulae Originally, the word "nebula" referred to almost any extended astronomical object other than planets and comets.
The word "nebula" comes from the Greek word for "cloud. Today, we reserve the word nebula for extended objects consisting mostly of gas and dust. Nebulae come in many shapes and sizes, and form in many ways. In some nebulae, stars form out of large clouds of gas and dust; once some stars have formed inside the cloud, their light illuminates the cloud, making it visible to us.
These star formation regions are sites of emission and reflection nebulae, like the famous Orion Nebula shown in the picture on the right. Emission nebulae are clouds of high temperature gas. The atoms in the cloud are energized by ultraviolet light from a nearby star and emit radiation as they fall back into lower energy states neon lights glow in much the same way.
Emission nebulae are usually red, because hydrogen, the most common gas in the universe, most commonly emits red light. Reflection nebulae are clouds of dust that simply reflect the light of a nearby star or stars. Reflection nebulae are usually blue, because blue light scatters more easily. Emission and reflection nebulae are often seen together and are sometimes both referred to as diffuse nebulae. In some nebulae, the star formation regions are so dense and thick that light cannot get through.
Not surprisingly, these are called dark nebulae. Another type of nebula, called a planetary nebula, results from the death of a star. Vastly bigger collections of stars are galaxies, far beyond the Milky Way, which appear as fuzzy blurs in the night sky.
You will need binoculars or a telescope to see all but the very closest and brightest. So although nebulae and galaxies are quite different astronomical objects, they are similar in that both look like fuzzy blobs to the casual stargazer. The Pleiades is a cluster of several thousand stars, but only the biggest and brightest 6 to 8 are visible to the unaided eye.
All the stars were born out of the same cloud of gas and dust about million years ago and will eventually drift apart. Galileo observed the cluster in and counted 40 stars. How many stars do you count in your OWN image?
Called a planetary nebula because it looks like a planet through small telescopes, the Ring Nebula is actually the outer atmosphere of a dying star. When a star like the Sun runs out of nuclear fuel, the outer atmosphere is blown off into space, creating a planetary nebula and leaving behind an Earth-sized core we call a white dwarf star.
Almost all the stars and nebulae you can see with the MicroObservatory telescopes are part of our own Milky Way galaxy. Our galaxy is a large disk-shaped spiral of around billion stars, but here on Earth we view the disk from the inside, and so see a milky band of light across the sky.
Galileo first resolved this cloudy band into "countless stars" when he turned his telescope skyward in If you take your OWN wide-field view of the Milky Way, look for huge clouds of gas and dust nebulae in addition to countless stars.
Look towards the constellation Sagittarius and you look towards the center of our galaxy. Beyond the impenetrable curtain of stars and dust lies Sagittarius A, a turbulent and dangerous place filled with X-ray hot gas and the remnants of exploded stars. The stars you see in your OWN image are just the brightest and closest of billions of stars lying between us and the very heart of our galaxy. An expanding shell of gas from a dying star that was similar to the Sun, the Dumbbell Nebula may offer a glimpse into the future of our own star.
Although the Sun has five billion years of nuclear fuel left, the star that created the Dumbbell exhausted its fuel over 50, years ago. In its death throes, the star blew off its outer layers to form the beautiful ghostly nebula we see today.
The nebula got its popular name because of a double lobe appearance. What shape do you see in your OWN image? The Trifid Nebula is a stellar nursery, where young hot stars are illuminating the cocoon of gas surrounding them. The light reaching us comes directly from the hot gas, but also from starlight reflected from the dust of the cocoon. It was called the Trifid because in early observations it appeared to be broken into three bright regions by the dust lanes that cross the nebula.
How many dust lanes can you see in your OWN image? Resembling a pool of light in the sky, the Lagoon Nebula is a giant cloud of hot hydrogen gas glowing from the intense light of newborn stars. The Lagoon Nebula, like other star-forming regions, can give us an insight into the environment that gave birth to our own Sun 5 billion years ago. What color does the Lagoon look in your OWN color image? The Eagle Nebula is an immense star-forming region, where the intense radiation and winds from newborn stars are sweeping away the dust and gas that was left over from their formation.
Because of these forces, the majestic dusty pillars that give the Eagle its name will evaporate over the next few million years. Can you match the two? The Crab Nebula is the twisted remains of a giant star that was seen to explode in the year As the outer parts of the stars exploded, the massive core of the star squeezed down to form a city-sized ball of neutrons called a pulsar.
Spinning on its axis 30 times a second, the intense magnetic fields of the Crab pulsar power the expansion of the nebula.
The first confirmed discovery of a black hole, Cygnus X-1 is a binary system of a normal star and a massive but invisible companion. The black hole reveals its presence in two ways: its gravitational tug on the visible star, and a glow of X-rays as gas from the star is pulled into the black hole. Your OWN image will only reveal the visible companion star of the black hole.
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