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Space - the Final Trivia Frontier

topic posted Sat, March 15, 2008 - 7:46 AM by  Craig
OK, OK, Bloke has been after me to start a thread on astronomy and spaceflight trivia, and since he's sick and all, I give in. :D

First up: Ten things you don’t know about the Milky Way Galaxy

1) It’s a barred spiral.

"You might know that the Milky Way is a spiral galaxy, perhaps the most beautiful galaxy type. But a lot of spirals have a weird feature: a rectangular block of stars at the center instead of a sphere, and the arms radiate away from the ends of the block. Astronomers call this block a bar, and, you guessed it: we have one."

2) There’s a supermassive black hole at its heart.

"It’s thought now that a supermassive black hole in the center of a galaxy forms along with the galaxy itself, and in facts winds blown outward as material falls in affects the formation of stars in the galaxy. So black holes may be dangerous, but it’s entirely possible the Sun’s eventual birth — and the Earth’s along with it — may have been lent a hand by the four million solar mass killer so far away."

3) It’s a cannibal.

"The Milky Way is pretty, but it’s savage, too. It’s currently eating several other galaxies. They’ve been ripped into long, curving arcs of stars that orbit the center of the Milky Way. Eventually they’ll merge completely with us, and we’ll be a slightly larger galaxy."

4) We live in a nice neighborhood…

"The Milky Way is not alone in space. We’re part of a small group of nearby galaxies called — get ready to be shocked — the Local Group. All together, there are something like three dozen galaxies in the Local Group, with most being dinky dwarf galaxies that are incredibly faint and difficult to detect."

5) … and we’re in the suburbs.

"The Local Group is small and cozy, and everyone makes sure their lawns are mowed and houses painted nicely. That’s because if you take the long view, we live in the suburbs. The big city in this picture is the Virgo Cluster, a huge collection of about 2000 galaxies, many of which are as large or larger than the Milky Way."

6) You can only see 0.000003% percent of it.

"When you got out on a dark night, you can see thousands of stars. But the Milky Way has two hundred billion stars in it. You’re only seeing a tiny tiny fraction of the number of stars tooling around the galaxy."

7) 90% of it is invisible.

"When you look at the motions of the stars in our galaxy, you can apply some math and physics and determine how much mass the galaxy has (more mass means more gravity, which means stars will move faster under its influence). You can also count up the number of stars in the galaxy and figure out how much mass they have. Problem is, the two numbers don’t match: stars (and other visible things like gas and dust) make up only 10% of the mass of the galaxy. Where’s the other 90%?"

8) Spiral arms are an illusion.

"Well, they’re not an illusion per se, but the number of stars in the spiral arms of our galaxy isn’t really very different than the number between the arms! The arms are like cosmic traffic jams, regions where the local density is enhanced."

9) It’s seriously warped.

"The Milky Way is a flat disk roughly 100,000 light years across and a few thousand light years thick (depending on how you measure it). It has the same proportion as a stack of four DVDs, if that helps.

Have you ever left a DVD out in the Sun? It can warp as it heats up, getting twisted (old vinyl LPs used to be very prone to this). The Milky Way has a similar warp!"

10) We’re going to get to know the Andromeda galaxy a lot better.

"The Andromeda Galaxy and the Milky Way are approaching each other, two cosmic steam engines chugging down the tracks at each other at 200 kilometers per second. Remember when I said big galaxies eat small ones? Well, when two big galaxies smack into each other, you get real fireworks."

Source, and the complete story:
www.badastronomy.com/bablog/...-galaxy/
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Craig
offline Craig
Minneapolis
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  • Craig
    Craig
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    The X-15

    Sat, March 15, 2008 - 7:36 PM
    OK, this is the craft that convinced the young and foolish Craig to want to be a test pilot when he grew up. Fortunately near-sightedness intervened. ;)

    "In the joint X-15 hypersonic research program that NASA conducted with the Air Force, the Navy, and North American Aviation, Inc., the aircraft flew over a period of nearly 10 years and set the world's unofficial speed and altitude records of 4,520 mph (Mach 6.7) and 354,200 feet in a program to investigate all aspects of piloted hypersonic flight. Information gained from the highly successful X-15 program contributed to the development of the Mercury, Gemini, and Apollo piloted spaceflight programs as well as the Space Shuttle program."

    "The X-15 was a follow-on research aircraft to the early X-planes, which had explored the flight regime from just below the speed of sound (Mach 1) to Mach 3.2. In 1952 the NACA had begun preliminary research into space flight and associated problems. Two years later, NACA's Research Airplane Projects Panel discussed the need for a new research airplane to study hypersonic and space flight. The NACA established the characteristics of what became the X-15 and presented them to the Air Force and Navy in July 1954. The two services and NACA signed a memorandum of understanding for the joint project in December 1954, and the Air Force selected North American to develop three X-15 research aircraft in September 1955."

    "The X-15 used conventional aerodynamic controls for flight in the dense air of the usable atmosphere. The controls consisted of rudder surfaces on the vertical stabilizers to control yaw (movement of the nose left or right) and canted horizontal surfaces on the tail to control pitch (nose up and down) when moving in synchronization or roll when moved differentially.

    For flight in the thin air outside the Earth's atmosphere, the X-15 used a reaction control system. Hydrogen peroxide thrust rockets on the nose of the aircraft provided pitch and yaw control. Those on the wings furnished roll control.

    The outer skin of the X-15 consisted of a nickel-chrome alloy called Inconel X, employed in a heat sink structure to withstand the results of aerodynamic heating when the aircraft was flying within the atmosphere. The cabin was made of aluminum and was isolated from the outer structure to keep it cool."

    "The distinguished Langley aeronautical researcher John Becker, who had been an early advocate of the X-15 program, identified 25 specific accomplishments of the effort. These included:

    First application of hypersonic theory and wind tunnel work to an actual flight vehicle.
    First use of reaction controls for attitude control in space.
    First reusable superalloy structure capable of withstanding the temperatures and thermal gradients of hypersonic reentry.
    Development of (a servo-actuated ball) nose flow direction sensor for operation over an extreme range of dynamic pressure and a stagnation air temperature of 1,900° F (for accurate measurement of air speed and flow angle at supersonic and hypersonic speeds).
    Development of the first practical full pressure suit for pilot protection in space.
    Development of inertial flight data systems capable of functioning in a high dynamic pressure and space environment.
    Discovery that hypersonic boundary layer flow is turbulent and not laminar.
    Discovery that turbulent heating rates are significantly lower than had been predicted by theory.
    First direct measurement of hypersonic aircraft skin friction and discovery that skin friction is lower than had been predicted.
    Discovery of hot spots generated by surface irregularities. (These last four discoveries including the Space Shuttle.)
    Discovery of methods to correlate base drag measurements with tunnel test results so as to correct wind tunnel data (and thereby improve design criteria for future air- and spacecraft).
    Demonstration of a pilot's ability to control a rocket boosted aerospace vehicle through atmospheric exit.
    Successful transition from aerodynamic controls to reaction controls and back again.
    First application of energy-management techniques (for the positioning of the vehicle for all future reusable launch vehicles following their reentry from space.)
    Use of the three X-15 aircraft as testbeds to carry a wide variety of experimental packages."

    Source: www.nasa.gov/centers/dry...52-DFRC.html
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  • Craig
    Craig
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    Re: Space - the Final Trivia Frontier

    Sat, March 15, 2008 - 8:09 PM
    Ooooh, and a fine Space Trivia question for y'all:

    Who came up with the theory of the origin of the Universe later commonly known as 'The Big Bang,' and what was it called originally?

    (Hint: he was a Roman Catholic priest.)
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    • Mart...
      Martinus
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      Re: Space - the Final Trivia Frontier

      Sun, March 16, 2008 - 12:49 PM
      Well the expanding universe theory actually developed after the first observations by Vesto Slipher in 1912 when he measured the first Dopler shift of a spiral nebula and discovered that all such observable nebula were seen to be receeding from us. Alexander Friedmann later derived equations showing that the universe might be expanding in contrast to the static universe model advocated by Einstein. Then in 1927, Georges Lemaître developed his own version of Friedmann's equations that predicted that the recession of the nebulae was due to the expansion of the universe. He later suggested that the evident expansion in forward time required that the universe contracted backwards in time until the entire universe was a single primeval atom.

      Meanwhile, Edwin Hubble discovered a correlation between distance and recession velocity—now known as Hubble's law and confirmed that the universe was expanding.

      After World War II, two distinct possibilities emerged. One was Fred Hoyle's steady state model, whereby new matter would be created as the universe seemed to expand. In this model, the universe is roughly the same at any point in time. The other was Lemaître's Big Bang theory, advocated and developed by George Gamow, who introduced big bang nucleosynthesis.

      The term "Big Bang" was first used by Sir Frederick Hoyle in an attempt to discredit the theory on a BBC radio program, The Nature of Things broadcast at 1830 GMT on 28 March 1949. While having no argument with the Lemaître theory, (later confirmed by Edwin Hubble's observations) that the universe was expanding, Hoyle disagreed on its interpretation. He found the idea that the universe had a beginning to be philosophically troubling, as many argued that a beginning implies a cause, and thus a creator. Instead, Hoyle, along with Thomas Gold and Hermann Bondi argued for the universe as being in a steady state.

      Eventually, the observational evidence, most notably from radio source counts, began to favor the latter. The discovery of the cosmic microwave background radiation in 1964 secured the Big Bang as the best theory of the origin and evolution of the cosmos.
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  • Craig
    Craig
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    Google Sky

    Sun, March 16, 2008 - 6:41 AM
    You're probably aware of Google Earth, but they also have a virtual astronomical observatory: Google Sky

    www.google.com/sky/

    "To help you explore the far reaches of our universe, we have teamed up with astronomers at some of the largest observatories in the world to bring you a new view of the sky. Using Google Maps this tool provides an exciting way to browse and explore the universe. You can find the positions of the planets and constellations on the sky and even watching the birth of distant galaxies as seen by the Hubble Space Telescope.

    We are particularly excited about the ability to view the universe at different wavelengths, to see how it would look if our eyes worked in the x-rays or infrared. As you explore these new layers, play with the transparency to blend between the different wavelengths and see how different parts of the universe light up at different wavelengths."
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