Tuesday, October 13, 2015

Largest Liquid Ocean in the Solar System: Jupiter's Liquid Metallic Hydrogen Sea

  •  The Solar System's biggest sea has yet to be found
  • It's not made of water or hydrocarbons 
  • It's not cold...in fact it's incredibly hot
  • Think liquid metal.
 
Artist's impressions of what the ocean could look like

August 5th 2011 NASA's Juno spacecraft blasted off on a 5-year voyage to a freakish world: planet Jupiter. 

Jupiter has a long list of oddities. For one thing, it's enormous, containing 70% of our solar system's planetary material, yet it is not like the rocky world beneath our feet. Jupiter is so gassy, it seems more like a star. Jupiter’s atmosphere brews hurricanes twice as wide as Earth itself, monsters that generate 400 mph winds and lightning 100 times brighter than terrestrial bolts. The giant planet also emits a brand of radiation lethal to unprotected humans. 

Jupiter's strangest feature, however, may be a 25,000 mile deep soup of exotic fluid sloshing around its interior. It's called liquid metallic hydrogen. 

"Here on Earth, hydrogen is a colorless, transparent gas," says Juno principal investigator Scott Bolton. "But in the core of Jupiter, hydrogen transforms into something bizarre." 
 
This cut-away illustrates a hypothesized model of the interior of Jupiter

Jupiter is 90% hydrogen, with 10% helium and a sprinkle of all the other elements. In the gas giant’s outer layers, hydrogen is a gas just like on Earth. As you go deeper, intense atmospheric pressure gradually turns the gas into a dense fluid. Eventually the pressure becomes so great that it squeezes the electrons out of the hydrogen atoms and the fluid starts to conduct like a metal.
What’s this fluid like? 

"Liquid metallic hydrogen has low viscosity, like water, and it's a good electrical and thermal conductor," says Caltech's David Stevenson, an expert in planet formation, evolution, and structure. "Like a mirror, it reflects light, so if you were immersed in it [here's hoping you never are], you wouldn't be able to see anything." 
Jupiter's hydrogen sea

Here on Earth, liquid metallic hydrogen has been made in shock wave experiments, but since it doesn't stay in that form it has only been made in tiny quantities for very short periods of time. If researchers are right, Jupiter's core may be filled with oceans of the stuff. 

There's so much LMH inside Jupiter that it transforms the planet into an enormous generator. "A deep layer of liquid metallic hydrogen and Jupiter's rapid rotation (about 10 hours) create a magnetic field 450 million miles long -- the biggest entity in the solar system," says Bolton. Jupiter's magnetosphere can produce up to 10 million amps of electric current, with auroras that light up Jupiter’s poles more brightly than any other planet. 
 
Although scientists are fairly sure that liquid metallic hydrogen exists inside Jupiter, they don't know exactly how the big planet's interior is structured. For instance, where does the hydrogen turn into a conductor? Does Jupiter have a core of heavy elements inside? 
Juno's mission is to answer those key questions. 
 "By mapping Jupiter's magnetic field, gravity field, and atmospheric composition, Juno will tell us a great deal about the make-up of Jupiter's interior." 

It's important to understand this behemoth because it wielded a lot of influence in the solar system's formation. After the sun took shape out of the solar nebula, Jupiter formed from the majority of leftover material. The state and composition of the material remaining just after the sun formed are preserved in Jupiter. 

"It holds the heirloom recipe that made our solar system's first planets," says Bolton. "And we want it."
With last Friday's launch, "Jupiter becomes our lab, Juno our instrument, to unlock the secrets of gas giants," he says. And what Juno discovers could be very freakish, indeed.
Credit: NASA

Tuesday, October 6, 2015

Rod from God - Kinetic Energy Weapons

Rod from God satellite
There's an urban legend about a woman killed by a shaft of frozen urine fallen from a plane's leaking toilet. Then there's the one about pennies dropped from the top of the Empire State Building, passing through pedestrians' skulls like bullets. Then there's the one about telephone pole-sized tungsten rods dropping from an orbital weapons platform at 36,000 feet per second to impact the earth below with the force of a meteor strike.

Guess which one you won't find on Snopes under "stupid bullshit?"
Yes, enormous Swords of Damocles hanging in space are one more reason to lie awake at night, thinking about how much safer we feel thanks to science.

Sunday, September 27, 2015

How dense is a Neutron Star?

  •  A neutron star is about 20 km in diameter and has the mass of about 1.4 times that of our Sun. 
  • One teaspoonful would weigh a billion tons (or more)
  •  Some neutron stars have jets of materials streaming out of them at nearly the speed of light. As these beams pan past Earth, they flash like the bulb of a lighthouse. This pulsing appearance led them to be called pulsars.

Friday, September 25, 2015

Lakes of Titan

  •  Titan harbours the only other verified bodies of liquid on the surface of a planet/moon
  • Lakes are composed of liquid methane 
  • Reaction between UV light and methane could produce organic molecules i.e. amino acids
  • Should we sit back and let it be?

Saturday, September 19, 2015

Mapping the Milky Way Inside Out

  • Using WISE (NASA's Wide-field Infrared Survey Explorer), the research team has discovered more than 400 dust-shrouded nurseries of stars, which trace the shape of our galaxy's spiral arms
  • The results support the four-arm model of our galaxy's spiral structure.
  •  The spacecraft was put into hibernation mode in 2011, after it scanned the entire sky twice
  • In September 2013, WISE was reactivated

Monday, September 7, 2015

Downfall of the Modern World - Solar Storms

  •  Solar storms pose more danger than ever recorded in human history
  • Centuries of technological advanced could be wiped in the worst case scenario
  • The Sun has fired a warning shot before
  • Civilization must take steps to reduce risks

Thursday, August 6, 2015

What if the Earth suddenly stopped spinning?

  •  What if the Earth's core stopped spinning? (Like in the move 'The Core')
  • Since the Earth spins at around 1000mph, what if that suddenly stopped
  • Would we all be done for?
  • What if there was no more magnetosphere?

Tuesday, July 28, 2015

Weakening of the Earth's Magnetosphere 10x faster than hypothesized


  • Data was collected by the European Space Agency's Swarm satellites
  • First data set reveals dramatic declines over the Western hemisphere, but a strengthening of the Earth's magnetic field over the southern Indian Ocean
  • Changes could be due to the magnetic poles getting ready to 'flip'
  • Latest measurements confirm movement of magnetic North towards Siberia
  • Scientists previously estimated the Earth’s magnetic field is weakening at five per cent every century and now think it could be 10 times as fast


  • Does this mean we'll face the brunt of the Sun's radiation?


    Saturday, July 25, 2015

    Huge explosions from Magnetic Reconnections

    Large flares are often associated with huge ejections of mass from the Sun, although the association is not clear. These coronal mass ejections (CMEs) are balloon-shaped bursts of solar wind rising above the solar corona, expanding as they climb. Solar plasma is heated to tens of millions of degrees, and electrons, protons, and heavy nuclei are accelerated to near the speed of light. The super-heated electrons from CMEs move along the magnetic field lines faster than the solar wind can flow.

    CMEs are not small either...
    Rearrangement of the magnetic field, and solar flares may result in the formation of a shock that accelerates particles ahead of the CME loop. Each CME releases up to 100 billion kg (220 billion lb) of this material, and the speed of the ejection can reach 1000 km/second (2 million mph) in some flares. Solar flares and CMEs are currently the biggest "explosions" in our solar system, roughly approaching the power in one billion hydrogen atomic bombs.

    Wednesday, July 15, 2015

    Welcome to the Magnetic Apocalypse

    Expect electrically charged storms, rising tides and power outages
    For scary speculation about the end of civilization in 2012, people usually turn to followers of cryptic Mayan prophecy, not scientists. But that’s exactly what a group of NASA-assembled researchers described in a chilling report issued earlier this year on the destructive potential of solar storms.
    Entitled “Severe Space Weather Events — Understanding Societal and Economic Impacts,” it describes the consequences of solar flares unleashing waves of energy that could disrupt Earth’s magnetic field, overwhelming high-voltage transformers with vast electrical currents and short-circuiting energy grids. Such a catastrophe would cost the United States “$1 trillion to $2 trillion in the first year,” concluded the panel, and “full recovery could take four to 10 years.” That would, of course, be just a fraction of global damages.

    Sunday, May 31, 2015

    Human settlements vs Martian dust storms

    *From the MarsOne website
    The environment of Mars contains dust that is much finer than that found on Earth. While the exact effects of this fine dust on technical hardware and equipment are not fully known, it is not impossible to engineer equipment to survive it. The NASA rovers Spirit and Opportunity were designed to operate for a minimum of 90 days, but have exceeded their target lifespans substantially. Spirit lasted about 1900 days. Opportunity is still driving around and investigating Mars since January 2004.

    It is unknown how the fine Mars dust might affect humans, should they be exposed to it. However, the astronauts will only go outside in their fully-enclosed Mars suits, and inside the habitat, the air will be filtered to remove the dust.

    Thursday, May 21, 2015

    Ballooning around on Mars

    Balloons provide a unique vantage point for scientific observation. Balloons can fly one hundred times closer to the surface of Mars than orbiters and can travel a thousand times further than rovers in a comparable period, thus providing views of much broader areas of the surface.

    Proposed use of balloons on Mars


    Wednesday, May 20, 2015

    Breathing in the air on Mars

    The air on Mars would kill a human quickly. The atmosphere is less than 1% of Earth’s, so it would be hard to breath. What you would have available to your lungs would be undesirable to say the least. The air on Mars consists of 95% carbon dioxide, 3% nitrogen, 1.6% argon, and the remainder is trace amounts of oxygen, water vapor, and other gases.
     
    Mars soil is though to contain oxygen rich particles


    Thursday, May 14, 2015

    Battling solares flares on Mars

    An incredible burst of energy and particles
    Work on solar flares could prove important for future missions to Mars that might eventually be part of a plan outlined by President Bush in 2004. On Earth, solar flares have been known to damage or skew results from satellites such as those making up the Global Positioning System (GPS).
    "If humans go to Mars and have a similar positioning system there, knowing about ionosphere effects will be important," Withers said.

    Thursday, May 7, 2015

    Choking atmosphere on Mars

    Mars has a thin atmosphere — too thin to easily support life as we know it. The extremely thin air on Mars can also become very dusty. Giant dust storms can blanket the entire planet and last for months.

    What is Mars' atmosphere made of?

    The atmosphere of Mars is about 100 times thinner than Earth's, and it is 95 percent carbon dioxide. Here's a breakdown of its composition:
    • Carbon dioxide: 95.32 percent
    • Nitrogen: 2.7 percent
    • Argon: 1.6 percent
    • Oxygen: 0.13 percent
    • Carbon monoxide: 0.08 percent
    • Also, minor amounts of: water, nitrogen oxide, neon, hydrogen-deuterium-oxygen, krypton and xenon


    Sunday, May 3, 2015

    Valles Marineris: Quick facts

    1. It's the longest system of canyons in the Solar System, at over 4000 km long. If you were to drive a car at 100 km/h (60 miles per hour), it would take you over 40 hours to drive the length of Valles Marineris. It would be like driving from Madrid to Moscow.

    This artist's depiction gives you an idea of how big this landmark is

    Sunday, April 26, 2015

    Obstacles blocking colonization of Mars

    Getting to Mars
    With current rocket technology, it takes between seven and nine months to reach Mars. That’s a long time to be cooped up inside a tiny spacecraft with, presumably, a small number of crewmates.
    The potential psychological effects of such isolation are not fully known, although there are parallels here on Earth with long-duration submarine deployments and wintering expeditions in Antarctica.
    NASA announces world's biggest-ever rocket to take man to Mars and beyond
    Then there are the physical health issues — in weightlessness, your bones and muscles begin to deteriorate. Astronauts aboard the International Space Station take regular exercise, but even that does not fully stop the decline.
    And then there’s food. Who wants to spend seven months eating instant meals? Growing some edible plants during the journey sounds like a good idea, but it’s a bit of a risky proposition — what happens if your crops fail?

    Wednesday, April 8, 2015

    Making and storing anti-matter

    Fictitious antimatter trap from movie Angels & Demons
    If we really wish to fathom the mysteries of antimatter, we must first get to grips with the stuff itself. Easier said than done. How on earth do you pin down a substance that vanishes the moment it touches anything?

    Although it sounds exotic, antimatter would look no different to matter if you came across a lump of it. Even individual atoms of matter and antimatter would be indistinguishable. It’s only inside the atoms that their true nature is evident.

    Sunday, April 5, 2015

    Bring the Warp Drive to life: Alcubierre Warp Drive

    The Alcubierre drive or Alcubierre metric is a speculative idea based on a solution of Einstein's field equations in general relativity as proposed by theoretical physicist Miguel Alcubierre, by which a spacecraft could achieve faster-than-light travel if a configurable energy-density field lower than that of vacuum (i.e. negative mass) could be created. Rather than exceeding the speed of light within a local reference frame, a spacecraft would traverse distances by contracting space in front of it and expanding space behind it, resulting in effective faster-than-light travel.


    Thursday, April 2, 2015

    Anti matter & Fusion drives to take us to the stars

    Artist's conception of an antimatter rocket
    Nuclear fusion reactions sparked by beams of antimatter could be propelling ultra-fast spaceships on long journeys before the end of the century, researchers say.

    A fusion-powered spacecraft could reach Jupiter within four months, potentially opening up parts of the outer solar system to manned exploration, according to a 2010 NASA report.

    A number of hurdles would have to be overcome ― particularly in the production and storage of antimatter ― to make the technology feasible, but some experts imagine it could be ready to go in a half-century or so.

    Monday, March 30, 2015

    Nuclear fusion rockets to propel us into the future

    Rockets that harness the power of nuclear fusion may provide the next big leap in humanity's quest to explore the final frontier, NASA's science chief says.

    Lockheed's Skunk works facility has made many breakthroughs of late

    Nuclear fusion rockets could slash travel times through deep space dramatically, potentially opening up vast swathes of the solar system to human exploration, said John Grunsfeld, associate administrator for NASA's Science Mission Directorate.

    "It's transformative," Grunsfeld said last month after his presentation at Maker Faire Bay Area in San Mateo, Calif., a two-day celebration of DIY science, technology and engineering. "You could get to Saturn in a couple of months. How fantastic would that be?"

    For a little perspective: NASA's robotic Cassini spacecraft blasted off in October 1997 and didn't enter Saturn orbit until July 2004.

    Wednesday, March 25, 2015

    Project Orion: the good, the bad and the ugly

    Project Orion was a study of a spacecraft intended to be directly propelled by a series of explosions of atomic bombs behind the craft (nuclear pulse propulsion). Early versions of this vehicle were proposed to take off from the ground with significant associated nuclear fallout; later versions were presented for use only in space.

    Key components of the Orion drive

    Sunday, March 15, 2015

    Solar sails to take us to the nearest stars

    While rocket fuel has provided the energy for most space travel so far, solar energy may provide the boost for spaceships in the future. Just like cloth sails harness the wind, giant reflective sheets called solar sails can harness the sun's energy . These sheets could save fuel and provide maneuverability, but cannot function deep in space.

    Artist concept of a solar sail in space
    Solar sails work by capturing the energy from light particles as they bounce off a reflective surface, according to the Department of Energy. Each light particle has momentum, and when it strikes a reflective surface, it imparts that momentum to the reflective sheet, just like a collision of two billiard balls.

    As billions of light particles hit the sheet, they push the sail strongly enough to move a spacecraft. Over time, the solar particles could keep pushing a spaceship faster and faster, allowing it to attain very high speeds, according to scientists at Argonne National Laboratory.

    Achieving invisibility using science

    Scientists at the University of Rochester have discovered a way to hide large objects from sight using inexpensive and readily available lenses, a technology that seems to have sprung from the pages of J.K. Rowling's Harry Potter fantasy series.

    Cloaking is the process by which an object becomes hidden from view, while everything else around the cloaked object appears undisturbed.

    "A lot of people have worked on a lot of different aspects of optical cloaking for years," John Howell, a professor of physics at the upstate New York school, said on Friday.

    A laser shows the paths that light rays travel through the system, showing regions that can be used for cloaking an object. Photo: University of Rochester

    Monday, March 9, 2015

    The most commonly reported shapes of UFOs

    A mother ship resembling a giant football, a whirling coin-shaped disk that flashes across the sky, a diamond-shaped craft with a brilliant, mirror-like surface…
    These are among the most common UFO shapes, according to veteran UFO researcher Brad Steiger, author of Mysteries of Time and Space.
    Here are detailed descriptions based on Steiger’s analysis of several thousand sightings over the past 40 years:

    8. BLINDING LIGHT. Typically spotted at night, this UFO doesn’t have a definite shape – it’s simply a dazzling orange light. “But it moves methodically, as if guided by some form of alien intelligence.”  

    Thursday, March 5, 2015

    UFOs - Impossible maneuvers, defying physics and time

    Kenneth Arnold, first UFO sighting in history
    You have only to read or hear a few flying saucer reports to realize that aerodynamically something very interesting is involved. In both speed and maneuverability the UFO is remarkable. If it is a machine - and I think it is - it is surely a terrific one. It represents a level of scientific development far beyond anything dreamed by terrestrial science.

    This can best be demonstrated by quoting a few instances. When, for example, UFOs first came to public attention in the late 1940s, their superior performance was immediately apparent. The report of Kenneth Arnold, the Washington state businessman who saw, if not the first flying saucer in history, certainly the first one in which the world took an interest, illustrates the point.

    Tuesday, February 24, 2015

    The Surface of Venus

    Venus and Earth are often called twins because they are similar in size, mass, density, composition and gravity. However, the similarities end there.

    Venus is the hottest world in the solar system. Although Venus is not the planet closest to the sun, its dense atmosphere traps heat in a runaway version of the greenhouse effect that warms Earth.

    Murky clouds shroud the secrets of Venus

    Friday, February 20, 2015

    Red Giant Sun: A New Habitable Zone

    When the sun becomes a red giant, the simple calculation would put its equator out past Mars. All of the inner planets would be consumed.

    However, as the Sun reaches this late stage in its stellar evolution, it loses a tremendous amount of mass through powerful stellar winds. As it grows, it loses mass, causing the planets to spiral outwards. So the question is, will the expanding Sun overtake the planets spiraling outwards, or will Earth (and maybe even Venus) escape its grasp.


    Red Giant Diagram


    Ordovician-Silurian Mass Extinction

    The third largest extinction in Earth's history, the Ordovician-Silurian mass extinction had two peak dying times separated by hundreds of thousands of years. During the Ordovician, most life was in the sea, so it was sea creatures such as trilobites, brachiopods and graptolites that were drastically reduced in number. In all, some 85% of sea life was wiped out. An ice age has been blamed for the extinctions - a huge ice sheet in the southern hemisphere caused climate change and a fall in sea level, and messed with the chemistry of the oceans.

    A diorama portraying the seas of the Ordovician Period (from the Exhibit Museum, University of Michigan)

    Monday, February 16, 2015

    What lies at the edge of the Universe?

    Commonly asked question regarding the size of the Universe:


    Does the Universe have an edge, beyond which there is nothing?

    Galaxies extend as far as we can detect... with no sign of diminishing.There is no evidence that the universe has an edge. The part of the universe we can observe from Earth is filled more or less uniformly with galaxies extending in every direction as far as we can see - more than 10 billion light-years, or about 6 billion trillion miles. We know that the galaxies must extend much further than we can see, but we do not know whether the universe is infinite or not. When astronomers sometimes refer (carelessly!) to galaxies "near the edge of the universe," they are referring only to the edge of the OBSERVABLE universe - i.e., the part we can see.

    Timeline of the Universe


    Why can't we see the whole universe?

    Saturday, February 14, 2015

    Crystals at the Centre of the Earth

    A Seismic Adventure

    There's a giant crystal buried deep within the Earth, at the very center, more than 3,000 miles down. It may sound like the latest fantasy adventure game or a new Indiana Jones movie, but it happens to be what scientists discovered in 1995 with a sophisticated computer model of Earth's inner core. This remarkable finding, which offers plausible solutions to some perplexing geophysical puzzles, is transforming what Earth scientists think about the most remote part of our planet.

    Friday, February 13, 2015

    The Late Heavy Bombardment

    About 4 to 3.8 billion years ago a period of intense comet and asteroid bombardment is thought to have peppered all the planets including the Earth. Many of the numerous craters found on the Moon and other bodies in the Solar System record this event.
    One theory holds that a gravitational surge caused by the orbital interaction of Jupiter and Saturn sent Neptune careening into the ring of comets in the outer Solar System. The disrupted comets were sent in all directions and collided with the planets. These water-rich objects may have provided much of the water in the Earth's oceans.
    The record of this event is all but lost on the Earth because our planet's tectonic plate system and active erosion ensure that the surface is constantly renewed.

    Monday, February 9, 2015

    Saturn: The Crown Jewel of the Solar System

    Saturn is the sixth planet from the sun and the second largest planet in the solar system. Saturn was the Roman name for Cronus, the lord of the Titans in Greek mythology. Saturn is the root of the English word "Saturday."

    Saturn is the farthest planet from Earth visible to the naked human eye, but it is through a telescope that the planet's most outstanding features can be seen: Saturn's rings. Although the other gas giants in the solar system — Jupiter, Uranus and Neptune — also have rings, those of Saturn are without a doubt the most extraordinary.



    10 Interesting Facts About Saturn:

    Sunday, February 8, 2015

    Redefining the runt of the Solar System: Mercury

    The smallest of the planets in the Solar System, Mercury is an interesting place. Incredibly dense due to its proportionately large core Mercury is thought to have been once a much larger planet. 

    Mercury is the smallest planet — it is only slightly larger than Earth's moon. Since it has no significant atmosphere to stop impacts, the planet is pockmarked with craters. About 4 billion years ago, an asteroid roughly 60 miles (100 kilometers) wide struck Mercury with an impact equal to 1 trillion 1-megaton bombs, creating a vast impact crater roughly 960 miles (1,550 km) wide. Known as the Caloris Basin, this crater could hold the entire state of Texas. Another large impact may have helped create the planet’s odd spin. 

    10 Important Facts About Mercury:

    Saturday, January 24, 2015

    What if the Moon suddenly disappeared?

    What if we had no Moon?
    Or what if the we had a Moon like we do now and it suddenly disappeared?
    Find out what would happen.
     


    1.) There’d be no such thing as eclipses on Earth.
    Without the Sun, Moon and Earth, there would be no eclipses. The Sun is constantly shining on Earth, casting a shadow for over a million miles (and over a million kilometers) in its wake. Yet without our Moon — just a few hundred thousand miles (or kilometers) away — there’d be no object that would pass through the Earth’s shadow; there’d be no lunar eclipses.
    There’d also be no solar eclipses: no annular, partial, or total eclipses. The Moon’s shadow is almost exactly equal in length to the Earth-Moon distance; without the Moon, no shadow, and no disc to block the Sun’s disk. The next largest object that can pass in between the Earth (after the Moon) is Venus, and while it’s incredibly cool when that happens, that’s the closest we’d get to an eclipse without the Moon.

    Wednesday, January 21, 2015

    The mystery known as Sedna

    90377 Sedna is a large planetoid in the outer reaches of the Solar System that was, as of 2012, about three times as far from the Sun as Neptune. Spectroscopy has revealed that Sedna's surface composition is similar to that of some other trans-Neptunian objects, being largely a mixture of water, methane and nitrogen ices with tholins. Its surface is one of the reddest among Solar System objects. It is most likely a dwarf planet.

    Artist's conception of the surface of Sedna, with the Milky Way, Antares, the Sun and Spica above
    Astronomer Michael E. Brown, co-discoverer of Sedna and the dwarf planets Eris, Haumea, and Makemake, believes it to be the most scientifically important trans-Neptunian object found to date, because understanding its unusual orbit is likely to yield valuable information about the origin and early evolution of the Solar System.
     

    Thursday, January 15, 2015

    Nemesis: The Solar System's Second Star

    In 1983, a scientist named Richard Muller came up with an interesting theory to explain the almost regular intervals between mass extinctions on Earth.

    Roughly every 26 million years, the Earth suffers a massive extinction event in which whole species and ecosystems disappear.  It's widely believed and accepted by the scientific community  that the extinction events are precipitated by the impacts of comets and asteroid impacts, but what Muller devised to explain the almost regular event was rather scandalous - what if the sun had an evil twin brother?

    Saturday, January 10, 2015

    VY Canis Majoris

    Of all known stars, the VY Canis Majoris is the largest. This red Hypergiant star, found in the constellation Canis Major, is estimated to have a radius at least 1,800 that of the Sun’s. In astronomy-speak we use the term 1,800 solar radii to refer to this particular size. Although not the most luminous among all known stars, it still ranks among the top 50.





    Hypergiants are the most massive and luminous of stars. As such, they emit energy at a very fast rate. Thus, hypergiants only last for a few million years. Compare that to the Sun and similar stars that can keep on burning up to 10 billion years. VY Canis Majoris a.k.a. VY CMa is about 4,900 light years from the Earth.

    The radius has been estimated to come in at about 8.2AU (possibly even up to 10.2AU!), but the term, ‘surface,’ has no real definition here. You see, in the outer layers of the star, its density is so low, that it may be more comparable to a vacuum than a star. Its gargantuan size and properties have even sparked debate as to whether or not we can consider it a definite star, or if its more akin to a spherical nebula burning at 3000k! It is generally agreed that it is a star – and it isn’t alone. VY CMa belongs to a very exclusive group of stars, dubbed hypergiants. Hypergiants are so massive that they devour themselves at exponential rates – in other words, the amount of energy our Sun emits in year is equal to what a hypergiant would release in just 6 seconds.

    Wednesday, January 7, 2015

    Falling into a black hole: The singularity and spagettification

    If you were falling toward a black hole, most of the time you would simply feel weightless. The gravity of a black hole is just like the gravity of any other large mass, as long as you don’t get too close.

    Suppose you were falling feet first toward a black hole. As you got closer, your feet would feel a stronger force than your head, for example. These differences in forces are called tidal forces. Because of the tidal forces it would feel as if you are being stretched head to toe, while your sides would feel like they are being pushed inward. Eventually the tidal forces would become so strong that they would rip you apart. This effect of tidal stretching is sometimes referred to as spaghettification.

    Black Hole versus the Earth

    There are two predominant types of black hole in the universe. The first are supermassive black holes found churning at the centre of galaxies. These don’t really pose any threat to us, until our galaxy collides with another like the Andromeda galaxy in a few billion years.

    The other type are interstellar black holes, those formed when a large star goes supernova. These can be just a dozen or so miles across, with one of the closest to us being Cygnus X-1 about 6,000 light-years away measuring 44 kilometres (27 miles) in diameter. If a black hole like Cygnus X-1 were to stray near the Solar System, within a light-year or so, its gravity would cause chaos. The orbits of the outer planets and comets would be significantly and possibly disastrously altered, and this would in turn threaten the orbits of the inner planets and even the Sun. However, if the black hole passed directly through the Solar System, then things get immeasurably worse.

    Sunday, January 4, 2015

    The Oort Cloud vs Kuiper Belt

    • The Kuiper Belt and the Oort Cloud are regions of space. The known icy worlds and comets in both regions are much smaller than Earth's moon. 
    • The Kuiper Belt and the Oort Cloud surround our sun, a star. The Kuiper Belt is a doughnut-shaped ring, extending just beyond the orbit of Neptune from about 30 to 55 AU. The Oort Cloud is a spherical shell, occupying space at a distance between five and 100 thousand AU.
    • Long-period comets (which take more than 200 years to orbit the sun) come from the Oort Cloud. Short-period comets (which take less than 200 years to orbit the Sun) originate in the Kuiper Belt.