1. NEBULA: A nebula (Latin for "cloud"; pl. nebulae, nebulæ, or nebulas) is an interstellar cloud of dust, hydrogen, helium and other ionized gases. Originally, nebula was a name for any diffuse astronomical object, including galaxies beyond the Milky Way. The Andromeda Galaxy, for instance, was referred to as the Andromeda Nebula (and spiral galaxies in general as "spiral nebulae") before the true nature of galaxies was confirmed in the early 20th century by Vesto Slipher, Edwin Hubble, and others. Most nebulae are of vast size, even hundreds of light years in diameter. Although denser than the space surrounding them, most nebulae are far less dense than any vacuum created in an Earthen environment – a nebular cloud the size of the Earth would have a total mass of only a few kilograms. Nebulae are often star-forming regions, such as in the "Pillars of Creation" in the Eagle Nebula. In these regions the formations of gas, dust, and other materials "clump" together to form larger masses, which attract further matter, and eventually will become massive enough to form stars. The remaining materials are then believed to form planets and other planetary system objects.
Many nebulae form from the gravitational collapse of gas in the interstellar medium. As the material collapses under its own weight, massive stars may form in the center, and their ultraviolet radiation ionizes the surrounding gas, making it visible at optical wavelengths.
Some nebulae are formed as the result of supernova explosions, the death throes of massive, short-lived stars. The materials thrown off from the supernova explosion are ionized by the energy and the compact object that it can produce.
Other nebulae may form as planetary nebulae. This is the final stage of a low-mass star's life, like Earth's Sun. When a star has lost enough material, its temperature increases and the ultraviolet radiation it emits can ionize the surrounding nebula that it has thrown off.
2. BLACK HOLES:
What Is a Black Hole? A black hole is a place in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying. Because no light can get out, people can't see black holes. They are invisible. Space telescopes with special tools can help find black holes. The special tools can see how stars that are very close to black holes act differently than other stars.
How Big Are Black Holes? Black holes can be big or small. Scientists think the smallest black holes are as small as just one atom. These black holes are very tiny but have the mass of a large mountain. Mass is the amount of matter, or "stuff," in an object. Another kind of black hole is called "stellar." Its mass can be up to 20 times more than the mass of the sun. There may be many, many stellar mass black holes in Earth's galaxy. Earth's galaxy is called the Milky Way.
The largest black holes are called "supermassive." These black holes have masses that are more than 1 million suns together. Scientists have found proof that every large galaxy contains a supermassive black hole at its center. The supermassive black hole at the center of the Milky Way galaxy is called Sagittarius A. It has a mass equal to about 4 million suns and would fit inside a very large ball that could hold a few million Earths.
How Do Black Holes Form? Scientists think the smallest black holes formed when the universe began. Stellar black holes are made when the center of a very big star falls in upon itself, or collapses. When this happens, it causes a supernova. A supernova is an exploding star that blasts part of the star into space. Scientists think supermassive black holes were made at the same time as the galaxy they are in.
If Black Holes Are "Black," How Do Scientists Know They Are There? A black hole can not be seen because strong gravity pulls all of the light into the middle of the black hole. But scientists can see how the strong gravity affects the stars and gas around the black hole. Scientists can study stars to find out if they are flying around, or orbiting, a black hole. When a black hole and a star are close together, high-energy light is made. This kind of light cannot be seen with human eyes. Scientists use satellites and telescopes in space to see the high-energy light.
3. Nancy Grace Roman (born May 16, 1925) is an American astronomer who was one of the first female executives at NASA. She is known to many as the "Mother of Hubble" for her role in planning the Hubble Space Telescope. Throughout her career, Roman has also been an active public speaker and educator, and an advocate for women in the sciences.
4. Lyman Spitzer, Jr. (1914—1997), a world-renowned theoretical astrophysicist, developed the concept of a telescope in space. In 1946 — more than a decade before the launch of the first satellite — Spitzer proposed the development of a large, space-based observatory that would not be hindered by Earth's atmospheric distortion and span a broad range of wavelengths. This lofty vision ultimately became the Hubble Space Telescope. Spitzer was instrumental in the design and development of the Hubble Space Telescope. Throughout the 1960s and 1970s, he was an enthusiastic lobbyist for the telescope, both with Congress and the scientific community. Even after Hubble's launch in 1990, Spitzer remained deeply involved in the program. Not only did he make some important astronomical observations with the telescope that was essentially his brainchild, but he also spent a great deal of time — right up until the end of his life — analyzing Hubble data. In addition to space astronomy, Spitzer's work greatly advanced knowledge in other fields, including stellar dynamics, plasma physics, and thermonuclear fusion.
5. A Cepheid variable (/ˈsɛfiːɪd/ or /ˈsiːfiːɪd/) is a star that pulsates radially, varying in both temperature and diameter to produce brightness changes with a well-defined stable period and amplitude. A strong direct relationship between a Cepheid variable's luminosity and pulsation period secures for Cepheids their status as important distance indicators for establishing the galactic and extragalactic distance scales.
6. Redshift and blueshift describe how light changes as objects in space (such as stars or galaxies) move closer or farther away from us. The concept is key to charting the universe's expansion.
7. PERKIN-ELMER “COVER-UP”:
Hughes, Perkin-Elmer to Pay U.S. for Hubble Telescope Flaw
October 05, 1993|RALPH VARTABEDIAN | LOS ANGELES TIMES STAFF WRITER
WASHINGTON — Hughes Aircraft and Perkin-Elmer Corp. agreed Monday to pay $25 million to head off a threatened government lawsuit charging them with liability for the defect that crippled the $2-billion Hubble space telescope, the Justice Department said Monday.
Under terms of the settlement, Perkin-Elmer, which owned the Danbury Optical System unit that produced the flawed mirror in the telescope, will pay $15 million. Los Angeles-based Hughes, which acquired the Danbury unit after the mirror was produced, will pay $10 million.
The agreement concludes a three-year investigation by the Justice Department and releases the two companies from any further liability claims. Hughes will pay its portion by forgoing fees it would otherwise have received from the National Aeronautics and Space Administration, while Perkin-Elmer will pay the $15 million.
The Justice Department asserted that the two companies knew or should have known about the defect. Hughes officials said Monday that they agreed to the settlement only as a goodwill gesture because NASA, the Hubble sponsor, is a valued customer.
8. Idea for Hubble repair device born in the shower
November 30, 1993|By Los Angeles Times
When NASA planned a space shuttle mission to fix the Hubble Space Telescope -- the orbiting observatory hobbled by a defective mirror -- the agency chose its most experienced astronauts, trained them exhaustively for 11 months and gave them 200 custom-made tools to do the job.
But once the six-man, one-woman crew begins its mission -- liftoff is scheduled for early tomorrow -- their most sophisticated piece of equipment will be something that was not dreamed up in a NASA research center, industry think-tank or university laboratory.
It was conceived in the shower of a German hotel room.
There, nearly three years ago, while preparing to ask a European Space Agency team if it had any idea how to fix the Hubble, NASA engineer James H. Crocker encountered a shower head that extended and adjusted to accommodate bathers of almost any height.
The invention it inspired -- specially ground mirrors on automated arms that reach into the space telescope's belly and flop into place like that adjustable shower head -- could do what once seemed impossible: install corrective optics to within a few millions of an inch inside an apparently inaccessible part of a satellite 300 miles above Earth.
9. Where do stars and planets come from?
According to our current understanding, a star and its planets form out of a collapsing cloud of dust and gas within a larger cloud called a nebula. As gravity pulls material in the collapsing cloud closer together, the center of the cloud gets more and more compressed and, in turn, gets hotter. This dense, hot core becomes the kernel of a new star.
Meanwhile, inherent motions within the collapsing cloud cause it to churn. As the cloud gets exceedingly compressed, much of the cloud begins rotating in the same direction. The rotating cloud eventually flattens into a disk that gets thinner as it spins, kind of like a spinning clump of dough flattening into the shape of a pizza. These "circumstellar" or "protoplanetary" disks, as astronomers call them, are the birthplaces of planets.
Small clumps of material within a disk stick together to form larger clumps. Eventually these clumps grow to become planets.
As a disk spins, the material within it travels around the star in the same direction. Eventually, the material in the disk will begin to stick together, somewhat like household dust sticking together to form dust bunnies. As these small clumps orbit within the disk, they sweep up surrounding material, growing bigger and bigger. The modest gravity of boulder-sized and larger chunks starts to pull in dust and other clumps. The bigger these conglomerates become, the more material they attract, and the bigger they get. Soon, the beginnings of planets — "planetesimals," as they are called — are taking shape.
10. How many stars are there?
It's easier to count stars when they are inside galaxies, since that's where they tend to cluster. To even begin to estimate the number of stars, then you would need to estimate the number of galaxies and come up with some sort of an average.
Some estimates peg the Milky Way's star mass as having 100 billion "solar masses," or 100 billion times the mass of the sun. Averaging out the types of stars within our galaxy, this would produce an answer of about 100 billion stars in the galaxy. This is subject to change, however, depending on how many stars are bigger and smaller than our own sun. Also, other estimates say the Milky Way could have 200 billion stars or more.
The number of galaxies is an astonishing number, however, as shown by some imaging experiments performed by the Hubble Space Telescope. Several times over the years, the telescope has pointed a detector at a tiny spot in the sky to count galaxies, performing the work again after the telescope was upgraded by astronauts during the shuttle era.
A 1995 exposure of a small spot in Ursa Major revealed about 3,000 faint galaxies. In 2003—2004, using upgraded instruments, scientists looked at a smaller spot in the constellation Fornax and found 10,000 galaxies. An even more detailed investigation in Fornax in 2012, with even better instruments, showed about 5,500 galaxies.
[Scientists] used a very rough estimate of 10 trillion galaxies in the universe. Multiplying that by the Milky Way's estimated 100 billion stars results in a large number indeed: 100 octillion stars, or 100,000,000,000,000,000,000,000,000,000 stars, or a "1" with 29 zeros after it. [Scientists] emphasized that [such a] number is likely a gross underestimation, as more detailed looks at the universe will show even more galaxies.
11. How Old is the Universe?
Age may only be a number, but when it comes to the age of the universe, it's a pretty important one. According to research, the universe is approximately 13.8 billion years old. How did scientists determine how many candles to put on the universe's birthday cake? They can determine the age of the universe using two different methods: by (1) studying the oldest objects within the universe and (2) measuring how fast it is expanding.
(1)The universe cannot be younger than the objects contained inside of it. By determining the ages of the oldest stars, scientists are able to put a limit on the age.
(2) The universe we live in is not flat and unchanging, but constantly expanding. If the expansion rate is known, scientists can work backwards to determine the universe's age, much like police officers can unravel the initial conditions that resulted in a traffic accident. Thus, finding the expansion rate of the universe — a number known as the Hubble constant — is key.
[Part of the answer to the question of expansion has to do with the presence of dark energy and dark matter (see links on my website for more about this).]
12. Black Holes (see above)
13. JAMES WEBB SPACE TELESCOPE
The James Webb Space Telescope (JWST) is a flagship-class space observatory under construction and scheduled to launch in October 2018. The JWST will offer unprecedented resolution and sensitivity from long-wavelength (orange-red) visible light, through near-infrared to the mid-infrared, and is a successor instrument to the Hubble Space Telescope and the Spitzer Space Telescope. The telescope features a segmented 6.5-meter (21 ft) diameter primary mirror and [will be in orbit beyond Earth’s moon.] A large sunshield will keep its mirror and four science instruments below 50 K (−220 °C; −370 °F).
JWST's capabilities will enable a broad range of investigations across the fields of astronomy and cosmology. One particular goal involves observing some of the most distant objects in the Universe, beyond the reach of current ground and space based instruments. This includes the very first stars, the epoch of reionization, and the formation of the first galaxies. Another goal is understanding the formation of stars and planets. This will include imaging molecular clouds and star-forming clusters, studying the debris disks around stars, direct imaging of exoplanets, and spectroscopic examination of planetary transits.