A Blog of Wisdom.: Astronomy

Top 10 Truth About Perseid Meteor Shower

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Perseids From the Sky 
 
Every August, the night sky is peppered with little bits of comet debris in what we call the annual Perseid meteor shower. The Perseids are bits of the comet Swift-Tuttle and often create the most amazing meteor shower of the year. 
 
Here are 10 cool facts you can use to impress friends and family late at night or early in the morning while watching for shooting stars: 
 
FIRST STOP: Perseids are FAST 
 
 
10 Perseids Aren't Slowpokes 
 
Perseid meteoroids (which is what they're called while in space) are fast. They enter Earth's atmosphere (and are then called meteors) at roughly 133,200 mph (60 kilometers per second) relative to the planet. Most are the size of sand grains; a few are as big as peas or marbles. Almost none hit the ground, but if one does, it's called a meteorite. 
 
9 Largest Object 
 
Comet Swift-Tuttle, whose debris creates the Perseids, is the largest object known to make repeated passes near Earth. Its nucleus is about 6 miles (9.7 kilometers) across, roughly equal to the object that wiped out the dinosaurs. 
 
8 Near-miss Coming? 
 
Back in the early 1990s, astronomer Brian Marsden calculated that Swift-Tuttle might actually hit Earth on a future pass. More observations quickly eliminated all possibility of a collision. Marsden found, however, that the comet and Earth might experience a cosmic near miss (about a million miles) in 3044. 
 
7 Heated Air 
 
When a Perseid particle enters the atmosphere, it compresses the air in front of it, which heats up. The meteor, in turn, can be heated to more than 3,000 degrees Fahrenheit (1,650 Celsius). The intense heat vaporizes most meteors, creating what we call shooting stars. Most become visible at around 60 miles up (97 kilometers). Some large meteors splatter, causing a brighter flash called a fireball, and sometimes an explosion that can often be heard from the ground. 
 
6 Lots of Comets 
 
Comet Swift-Tuttle has many comet kin. Most originate in the distant Oort cloud, which extends nearly halfway to the next star. The vast majority never visit the inner solar system. But a few, like Swift-Tuttle, have been gravitationally booted onto new trajectories, possibly by the gravity of a passing star long ago. 
 
5 Many Streams 
 
Perseid meteoroids (and if you've been following along, you know these are things in space before they hit Earth's atmosphere) are anywhere from 60 to 100 miles apart, even at the densest part of the river of debris left behind by comet Swift-Tuttle. That river, in fact, is more like many streams, each deposited during a different pass of the comet on its 130-year orbit around the Sun. The material drifts through space and, in fact, orbits the Sun on roughly the same path as the comet while also spreading out over time. 
 
4 Predawn Showers 
 
As Earth rotates, the side facing the direction of its orbit around the Sun tends to scoop up more space debris. This part of the sky is directly overhead at dawn. For this reason, the Perseids and other meteor showers (and also random shooting stars in general) are usually best viewed in the predawn hours. 
 
3 Last Time Around 
 
Comet Swift-Tuttle was last seen in 1992, an unspectacular pass through the inner solar system that required binoculars to enjoy. Prior to that, it had last been seen in the year it was "discovered" by American astronomers Lewis Swift and Horace Tuttle, 1862. Abraham Lincoln was president. 
 
2 Longtime Companion 
 
Swift-Tuttle's orbit has been traced back nearly 2,000 years and is now thought to be the same comet that was observed in 188 AD and possibly even as early as 69 BC. 
 
1 Next Time Around 
 
Swift-Tuttle is due back in 2126 (as you know now, it won't hit us) and astronomers think it might become a spectacular naked-eye comet like Hale-Bopp. If historical calculations are correct (see Fact #9) then the 2126 appearance will mark the comet's 3rd millennium of human observation, assuming someone is in fact around to see it. 
 
credit to <a href="http://www.space.com/12592-top-10-perseid-meteor-shower-facts.html">Space</a>

Perseids From the Sky Every August, the night sky is peppered with little bits of comet debris in what we call the annual Perseid meteo...

The Mystery of Venus’ Ashen Light

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May is the best time to try and spot one of the most enduring unsolved mysteries in our Solar System. Ashen Light is a faint glow allegedly seen on the unlit portion of Venus, during its crescent phase, similar to the earthshine often observed on the Moon, though not as bright. It is more commonly observed while Venus occupies the evening sky, as now, than when it is in the morning sky. But no one really knows for sure what causes it. 
 
So what’s the history of our knowledge about this enigmatic glow? 
 
The phenomenon was first noted in 1643, by Italian astronomer Giovanni Battista Riccioli. Though many notable astronomers have reported sightings in the 369 years since, including Sir William Herschel and more recently, Sir Patrick Moore, many others have failed to see the effect, leading to claims that it is due to nothing more than observer error, an illusion, atmospheric effect or equipment malfunction. Things are not helped by the fact that nobody has managed to capture an image of Ashen Light, yet. 
 
As the month progresses, Venus nears the Sun, ready for its transit on June 5th to 6th and the planet’s crescent phase will increase in diameter during the month, from 37 arcseconds to 56 arcseconds. The best option for amateur astronomers hoping to catch a fleeting glimpse is to use an occulting bar to block the bright crescent, making any glow present on the unlit portion of Venus, more visible. 
 
There is much controversy and many theories as to the cause of Ashen Light. The Keck 1 telescope on Hawaii reported seeing a subtle green glow and suggested it could be produced as ultraviolet light from the Sun splits molecules of carbon dioxide, known to be common in Venus’ atmosphere, into carbon monoxide and oxygen, but the green light emitted as oxygen recombines to form O2 is thought too faint to explain the effect. Another more likely theory is that multiple lightning strikes are illuminating Venus’ skies. Though the Cassini spacecraft flew by Venus twice on it’s voyage to Saturn and failed to detect the high frequency radio noise we associate with thunderstorms on Earth, in 2007 Venus Express did detect low frequency ‘whistler waves’ that can also result from lightning. It could also be the Venusian equivalent of aurorae. 
 
By far the most bizarre theory, and my personal favourite, was proposed in the early 19th century by the Bavarian astronomer Franz von Gruithuisen, who suggested that Ashen Light was the result of fires lit to clear land for farming on Venus, or to celebrate the coronation of a new Venusian Emperor! 
 
For further reading, <a href="http://www-ssc.igpp.ucla.edu/personnel/russell/papers/ashen/">a paper on Ashen Light by C. T. Russell and J. L. Phillips</a> 
 
credit to <a href="http://www.universetoday.com/94848/the-mystery-of-venus-ashen-light-2/">Universe Today</a>

May is the best time to try and spot one of the most enduring unsolved mysteries in our Solar System. Ashen Light is a faint glow allege...

10 Things You Should Know About Mars

Named for the Roman god of War, Mars probably got this name due to its red color. It is sometimes referred to as the Red Planet. The name of the month March derives from Mars. 
 
1. Mars is the fourth planet from the sun 
 
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Mars orbits the sun at an average distance of 141 million miles (approximately 1.5 AU), taking 686.93 Earth days or 1.8807 Earth years to complete a revolution. 
 
2. Mars is the seventh largest planet 
 
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At about half the diameter of Earth (about 4212 miles), with one tenth Earth's mass, Mars's gravity is about one third that of Earth. The density of Mars is about 30 percent less than that of Earth (3.94 g/cm3 vs. 5.52 g/cm3). Its core is probably similar to Earth's, mostly iron, with small amounts of nickel, but spacecraft mapping of its gravity field seem to indicate that its iron-rich core and mantle are a smaller portion of its volume than on Earth. Also, its smaller magnetic field than Earth, indicates a solid, rather than liquid core. 
 
3. Mars is a small rocky body 
 
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Like the other "terrestrial" planets - Mercury, Venus, and Earth - its surface has been changed by volcanism, impacts from other bodies, movements of its crust, and atmospheric effects such as dust storms. 
 
4. Mars's surface is closest to that of Earth of any of the planets 
 
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Still, it would still be a very harsh place to live, with temperature extremes between -225 and +60 degrees Fahrenheit, with an average of -67 degrees. 
 
5. Mars may be the best hope for finding life away from Earth 
 
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Mars has a very thin atmosphere made up mostly of a tiny amount of carbon dioxide (95.3%) plus nitrogen (2.7%), argon (1.6%) and traces of oxygen (0.15%) and water (0.03%). Also, water has been found to exist in liquid form on the planet. 
 
6. Mars has inspired wild flights of imagination over the centuries 
 
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Italian astronomer Giovanni Schiaparelli observed Mars during the opposition of 1877 making note of what he called canali or channels. This was misinterpreted to mean canals, which many thought to indicate intelligent life. 
In 1939, Orson Welles's radio theater company performed a production based on HG Wells's book "War of the Worlds" and caused a panic in many people who did not realize the event was merely a play. 
 
7. Mars has two tiny satellites which orbit very close to the surface 
 
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Phobos at a distance of 9000 km has a radius of 11 km and a mass of 1.08e16 kg. It was discovered by American astronomer Asaph Hall, Sr., in 1877, at the US Naval Observatory in Washington, DC. 
Deimos Distance at a distance of 23 has a radius of 6 km and a mass 1.80e15 kg. It was discovered by American astronomer Asaph Hall, Sr., in 1877, at the US Naval Observatory in Washington, DC. 
 
8. Mars has some remarkable geological characteristics 
 
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These include the largest volcanic mountain in the solar system, Olympus Mons (27 km high and 600 km across): volcanoes in the northern Tharsis region that are so huge they deform the planet's roundness; and a gigantic equatorial rift valley, the Valles Marineris. This canyon system stretches a distance equivalent to the distance from New York to Los Angeles; Arizona's Grand Canyon could easily fit into one of the side canyons of this great chasm. 
 
9. Mars has been visited by several probes 
 
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In 2004, a pair of rovers landed on Mars and started providing pictures and data. The Twin Mars Rovers, Spirit and Opportunity are providing NASA with some fascinating information about the red planet. In 2008, the Phoenix Lander touched down near the north pole and is also providing answers to other big questions. 
 
10. One day, humans will walk on Mars 
 
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NASA currently is planning a return to the moon in what is being called the first step towards a manned expedition to Mars. 
 
Credit to <a href="http://space.about.com/od/mars/tp/Mars10Things.htm">Space</a>

Named for the Roman god of War, Mars probably got this name due to its red color. It is sometimes referred to as the Red Planet. The name of...

10 Interesting Facts About Black Holes

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1: A black hole is formed when a large star starts running out of fuel and begins to collapse under its own gravity. Such a star may become a white dwarf or a neutron star, but if the star is sufficiently massive then it may continue shrinking eventually to the size of a tiny atom, known as a singularity or black hole. 
 
2: The mass of that shrunken star is so dense and the gravity of that singularity so strong that, in accordance with Einstein‘s theory of general relativity,  it actually deforms the space-time around it and not even light can escape. The boundary beyond which light cannot escape the black hole is known as the event horizon, while its radius is called the Schwarzschild radius. 
 
3: Once particles and light-rays go past the event horizon their light cones “tip over” and point to the singularity, which now represents all future-directed paths with no escape possible. 
 
4: To an outside observer with a telescope, an object passing the event horizon will appear to slow down then freeze without ever seeming to pass through the horizon. This is because the light takes longer to escape its gravitational pull and light signals won’t reach the viewer for an infinitely long time. As time elapses, the light becomes red shifted and dimmer as its wavelength becomes longer, eventually disappearing from the sight of the observer as it becomes infrared radiation, then radio waves. 
 
5: If a person was able to survive long enough to describe falling into a black hole, he would at first experience weightless as he goes into free fall, but then feel intense “tidal” gravitational forces as he got closer to the center of the black hole. In other words, if his feet were closer to the centre than his head, then they would feel a stronger pull until he eventually is stretched and then ripped apart. As he falls in he may observe distorted images as the light bends around him and he will also still be able to see beyond the black hole as light continues to reach him from the outside. 
 
6: It is important to realize that a black hole’s gravitational field is the same as that of any other object in space of the same mass. In other words, it won’t “suck” objects in any more than any other normal star, with things being more likely to just fall into them if they got too close to the event horizon. 
 
7: A wormhole, known alternatively as a Lorentzian wormhole, Schwarzschild wormhole or Einstein-Rosen bridge, is a theoretical opening in space-time allowing a “shortcut” through intervening space to another location in the Universe. However, from the outside wormholes may exhibit many of the characteristics usually associated with a black hole and be virtually impossible to tell apart. 
 
8: John Michell (1783) and Pierre-Simon Laplace (1796) were the first people to propose the concept of “dark stars” or object which, if compressed into a small enough radius, would have an escape velocity which exceeded even the speed of light. Later, the term “frozen star” was used to describe the last phase of a star’s gravitational collapse, when light unable to escape from its surface would make the star appear frozen in time to an observer. In the 20th century, John Wheeler eventually coined the phrase “black hole” as the object would absorbs all the light that hits it while reflecting nothing back. 
 
9: Physicists now believe that black holes actually radiate small numbers of mainly photon particles and so can lose mass, shrink then ultimately vanish over time. This unverified evaporation process is known as “Hawking Radiation”, after Professor Stephen Hawking who theorized its existence in 1974. However, it is a staggeringly slow process and only the smallest black holes would have had time to evaporate significantly during the 14 billion years the Universe has existed. 
 
10: It is now thought that most galaxies are held together by supermassive black holes at their centers, which cluster hundreds of solar systems around them. 
 
credit to <a href="http://www.astronomytrek.com/10-interesting-facts-about-black-holes/">astronomytrek</a>

1: A black hole is formed when a large star starts running out of fuel and begins to collapse under its own gravity. Such a star may bec...

Moon Facts

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There are many interesting facts about the moon and trivia that may or may not be important to you. Some interesting facts include: 
 
 
<ul>
<li>We all know there was a man on the moon, but did you know that there is one who stayed there? Dr. Eugene Shoemaker, a Geological Surveyor, who educated the Apollo mission astronauts about craters, never made it into space himself, but it had always been one of his dreams. He was rejected as an astronaut because of medical problems. After he died, his ashes were placed on board the Lunar Prospector spacecraft on January 6, 1999, which was crashed into a crater on the moon on July 31, 1999. The mission was to discover if there was water on the moon at the time, but it also served to fulfill Dr Shoemaker's last wish. </li>
</ul>
 
<ul>
<li>When Neil Armstrong took that first historical step and said "That's one small step for man, one giant leap for mankind" it would not have occurred to anyone that the step he took in the dust of the moon was there to stay. It will be there for millions of years because there is no wind on the moon. That is, assuming the downdraft from the Command Module upon takeoff back into space didn't destroy the print. Buzz Aldrin reportedly saw the American flag, much further away, blow over during launch. Nevertheless, any footprints made by the famous astronauts undisturbed by takeoff are, in fact, there to stay. </li>
</ul>
 
<ul>
<li>When Alan Sheppard was on the moon, he hit a golf ball and drove it 2,400 feet, nearly one half a mile. </li>
</ul>
 
<ul>
<li>In a survey conducted in 1988, 13% of those surveyed believed that the moon is made of cheese. </li>
</ul>
 
<ul>
<li>The multi layer space suits worn by the astronauts to the moon weighed 180 pounds on earth, but thirty pounds on the moon due to the lower gravity. </li>
</ul>
 
<ul>
<li>How close can you get without completely running out of gas? Apollo 11 had only 20 seconds of fuel left when they landed on the moon. </li>
</ul>
 
 
<ul>
<li>Apollo 15 was the first mission to use a lunar rover. The top speed that was ever recorded in this 4-wheeled land vehicle was 10.56 miles per hour. </li>
</ul>
 
 
<ul>
<li>It is possible to have a month without a full moon. This occurs in February, but either January or March will have two moons. </li>
</ul>
 
 
<ul>
<li>In China, the dark shadows that are on the moon are called "the toad in the moon". </li>
</ul>
 
 
<ul>
<li>The Apollo missions brought back 2196 rock samples weighing 382 kg in total</li>
</ul>
 
 
Facts About the Moon 
 
 
<ul>
<li>The moon is not a planet, but a satellite of the Earth. </li>
</ul>
<ul>
<li>The surface area of the moon is 14,658,000 square miles or 9.4 billion acres </li>
</ul>
<ul>
<li>Only 59% of the moon's surface is visible from earth. </li>
</ul>
<ul>
<li>The moon rotates at 10 miles per hour compared to the earth's rotation of 1000 miles per hour. </li>
</ul>
<ul>
<li>When a month has two full moons, the second full moon is called a blue moon. Another definition of a blue moon is the third full moon in any season (quarter of year) containing 4 total full moons. </li>
</ul>
<ul>
<li>From Earth, we always see the same side of the moon; the other side is always hidden. </li>
</ul>
<ul>
<li>The dark spots we see on the moon that create the image of the man in the moon are actually craters filled with basalt, which is a very dense material. </li>
</ul>
<ul>
<li>The moon is the only extraterrestrial body that has ever been visited by humans. It is also the only body that has had samples taken from it. </li>
</ul>
<ul>
<li>The first space craft to send back pictures from the moon was Luna 3 (built by the Soviet Union) in October 1959. </li>
</ul>
<ul>
<li>The moon has no global magnetic field. </li>
</ul>
<ul>
<li>The moon is about 1/4 the size of the Earth.</li>
</ul>
<div>
credit to www.moonconnection.com</div>

There are many interesting facts about the moon and trivia that may or may not be important to you. Some interesting facts include: ...

How The Aurora Borealis Form

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The amazing light appear to be seen in the sky. The colorful and beautiful light which never fail to please our eyes. Perhaps many of us love to watch this phenomena (normally occur in northern region). But do we really know how and what really made this happens?</div>
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It begins with a solar flare</div>
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The aurora borealis (northern lights) form when charged particles emitted from the sun during a solar flare penetrate the earth's magnetic shield and collide with atoms and molecules in our atmosphere. These collisions result in countless little bursts of light, called photons, which make up the aurora. Collisions with oxygen produce red and green auroras, while nitrogen produces the pink and purple colors. This reaction encircles the polar regions of the earth and occurs at an altitude of 40-400 miles (65-650 km) in a zone called the "Auroral Oval."</div>
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When and Where</div>
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The aurora borealis most commonly occur between 60°-75° latitude, but during great geomagnetic storms the auroral oval expands equatorially and can reach 30° latitude or further. In the northern hemisphere they are called the aurora borealis (northern lights) and in the southern hemisphere aurora australis (southern lights).</div>
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An auroral display might be observed any night from dusk until dawn as long as it is dark, which excludes Alaskan summer nights (May-July). The best time to view them is between midnight and 2 am. There is an 11-year solar cycle (on average) that controls the tempo of the aurora. The most recent peak in the cycle occurred in 2000-2001. The next peak is predicted in 2013 - 2014.</div>
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credit to aurorahunter.com</div>

The amazing light appear to be seen in the sky. The colorful and beautiful light which never fail to please our eyes. Perhaps many of u...

5 Interesting Concepts you probably didn’t know about the Universe

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The Universe that we inhabit is a mysterious, incomprehensible place that is so baffling at times that we fail to understand its underlying beauty and symmetry that impregnates it. Here are some of science’s most recent breakthroughs and discoveries. Some of them may seem incredible, but they are all valid scientific theories or proven concepts. 
 
1.We cannot observe the vast majority of the Universe. 
 
95 % of the Universe is presumed to be made up of dark energy or dark matter, which have both yet to be observed by scientists. Dark matter does not emit or reflect light or any other electromagnetic radiation, so is nearly impossible to be detected via optical or radio astronomy. Dark energy is more mysterious still, being a hypothetical form of energy to account for acceleration of the Universe. 
 
2.The Universe is flat. 
 
The Universe is an infinite flat shape. This theory was popularised when the Wilkinson Microwave Anisotropy Probe (WMAP) confirmed the existing knowledge with a 0.5% margin for error. Other shapes that have been considered are the spherical or hyperbolical universe, but these are now considered to be unlikely based on observations. 
 
3.Our Universe is one among the many. 
 
The Universe has been widely accepted to be part of the multiverse, a hypothetical set of universes that together comprise everything that exists and that can exist. The main hypothesis is that there are six types of ‘bubble universes’ that have different physical constants to our universe. This concept has been proposed to explain why our Universe seems to be fine-tuned for life as we experience it. Our universe is one in the near-infinite possibilities that emerged parallel to ours. 
 
4.The Universe as we know it will one day end. 
 
There are many theories surrounding the ultimate fate of the Universe, but nearly all scientifically accepted scenarios agree on one point: there is a point in time where our universe will cease to exist as we know it. We do not know whether this will be a result of a ‘Big Freeze’, where heat will become evenly distributed across an ever-expanding universe, or whether the Universe itself (in terms of the multiverse) will never cease to exist, and that our Universe is simply one in an infinite number of simultaneous Big Bangs, ever propagating outwards to infinity. 
 
5.There exist more than our four traditional dimensions. 
 
Our universe is made up of vibrating, hyper-energetic strings that exist in every dimension. Intriguingly, this theory predicts a greater number of dimensions than four, and that a certain number of these dimensions have been compacted and rolled up so that they are unobservable to current scientific means. This theory has yet to yield any quantitative results, and is still undergoing development. However, it is one of the main contenders for the Theory of Everything, a hypothetical theory that could unite the entirety of physics (quantum and general relativity). 
 
Not only do these recent scientific breakthroughs have incredible implications on how we perceive the universe, but they mean humans are closer than ever to solving the mysteries that have puzzled scientists for millennia and continue to today. Physics is relevant to all of us, because the beauty of the universe is all around us, and we can only truly appreciate its immensity and symmetry if we begin to understand what the universe really is. 
 
credit to olleycj.hubpages.com

The Universe that we inhabit is a mysterious, incomprehensible place that is so baffling at times that we fail to understand its underlyin...

10 Things You May Not Know About The Stars

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10) Every star you see in the night sky is bigger and brighter than our sun 
Of the 5,000 or so stars brighter than magnitude 6, only a handful of very faint stars are approximately the same size and brightness of our Sun and the rest are all bigger and brighter. Of the 500 or so that are brighter than 4th magnitude (which includes essentially every star visible to the unaided eye from a urban location), all are intrinsically bigger and brighter than our Sun, many by a large percentage. Of the brightest 50 stars visible to the human eye from Earth, the least intrinsically bright is Alpha Centauri, which is still more than 1.5 times more luminous than our Sun, and cannot be easily seen from most of the Northern Hemisphere. 
 
9) You can’t see millions of stars on a dark night 
Despite what you may hear in TV commercials, poems and songs, you cannot see a million stars … anywhere. There simply are not enough close enough and bright enough. On a really exceptional night, with no Moon and far from any source of lights, a person with very good eyesight may be able to see 2000-2500 stars at any one time. (Counting even this small number still would be difficult.). So the next time you hear someone claim to have seen a million stars in the sky, just appreciate it as artistic license or exuberant exaggeration – because it isn’t true! 
 
8) Red hot and cool ice blue – NOT! 
We are accustomed to referring to things that are red as hot and those that are blue as cool. This is not entirely unreasonable, since a red, glowing fireplace poker is hot and ice, especially in glaciers and polar regions, can have a bluish cast. But we say that only because our everyday experience is limited. In fact, heated objects change color as their temperature changes, and red represents the lowest temperature at which a heated object can glow in visible light. As it gets hotter, the color changes to white and ultimately to blue. So the red stars you see in the sky are the “coolest” (least hot), and the blue stars are the hottest! 
 
7) Stars are black bodies 
A black body is an object that absorbs 100 percent of all electromagnetic radiation (that is, light, radio waves and so on) that falls on it. A common image here is that of a brick oven with the interior painted black and the only opening a small window. All light that shines through the window is absorbed by the interior of the oven and none is reflected outside the oven. It is a perfect absorber. As it turns out, this definition of being perfect absorbers suits stars very well! However, this just says that a blackbody absorbs all the radiant energy that hits it, but does not forbid it from re-emitting the energy. In the case of a star, it absorbs all radiation that falls on it, but it also radiates back into space much more than it absorbs. Thus a star is a black body that glows with great brilliance! (An even more perfect black body is a black hole, but of course, it appears truly black, and radiates no light.) 
 
6) There are no green stars 
Although there are scattered claims for stars that appear green, including Beta Librae (Zuben Eschamali), most observers do not see green in any stars except as an optical effect from their telescopes, or else an idiosyncratic quirk of personal vision and contrast. Stars emit a spectrum (“rainbow”) of colors, including green, but the human eye-brain connection mixes the colors together in a manner that rarely if ever comes out green. One color can dominate the radiation, but within the range of wavelengths and intensities found in stars, greens get mixed with other colors, and the star appears white. For stars, the general colors are, from lower to higher temperatures, red, orange, yellow, white and blue. So as far as the human eye can tell, there are no green stars. 
 
5) The Sun is a green star 
That being said, the Sun is a “green” star, or more specifically, a green-blue star, whose peak wavelength lies clearly in the transition area on the spectrum between blue and green.  This is not just an idle fact, but is important because the temperature of a star is related to the color of its most predominate wavelength of emission. (Whew!) In the Sun’s case, the surface temperature is about 5,800 K, or 500 nanometers, a green-blue. However, as indicated above, when the human eye factors in the other colors around it, the Sun’s apparent color comes out a white or even a yellowish white. 
 
4) The Sun is a “dwarf” star 
We are accustomed to think of the Sun as a “normal” star, and in many respects, it is. But did you know that it is a “dwarf” star? You may have heard of a “white dwarf,” but that is not a regular star at all, but the corpse of a dead star. Technically, as far as “normal” stars go (that is, astronomical objects that produce their own energy through sustained and stable hydrogen fusion), there are only “dwarfs,” “giants” and “supergiants.” The giants and supergiants represent the terminal (old age) stages of stars, but the vast majority of stars, those in the long, mature stage of evolution (Main Sequence) are all called “dwarfs.” There is quite a bit of range in size here, but they are all much smaller than the giants and supergiants. So technically, the Sun is a dwarf star, sometimes called “Yellow Dwarf” in contradiction to the entry above! 
 
3) Stars don’t twinkle 
Stars appear to twinkle (“scintillate”), especially when they are near the horizon. One star, Sirius, twinkles, sparkles and flashes so much some times that people actually report it as a UFO. But in fact, the twinkling is not a property of the stars, but of Earth’s turbulent atmosphere. As the light from a star passes through the atmosphere, especially when the star appears near the horizon, it must pass through many layers of often rapidly differing density. This has the effect of deflecting the light slightly as it were a ball in a pinball machine. The light eventually gets to your eyes, but every deflection causes it to change slightly in color and intensity. The result is “twinkling.” Above the Earth’s atmosphere, stars do not twinkle. 
 
2) You can see 20 quadrillion miles, at least 
On a good night, you can see about 19,000,000,000,000,000 miles, easily. That’s 19 quadrillion miles, the approximate distance to the bright star Deneb in Cygnus. which is prominent in the evening skies of Fall and Winter. Deneb is bright enough to be seen virtually anywhere in the Northern hemisphere, and in fact from almost anywhere in the inhabited world. There is another star, Eta Carina, that is a little more than twice as far away, or about 44 quadrillion miles. But Eta Carina is faint, and not well placed for observers in most of the Northern hemisphere. Those are stars, but both the Andromeda Galaxy and the Triangulum Galaxy are also visible under certain conditions, and are roughly 15 and 18 quintillion miles away! (One quintillion is 10^18!) 
 
1) Black holes don’t “suck” 
Many writers frequently describe black holes as “sucking” in everything around them. And it is a common worry among the ill-informed that the so-far hypothetical “mini” black holes that may be produced by the Large Hadron Collider would suck in everything around them in an ever increasing vortex that would consume the Earth! “Say it ain’t so, Joe!” Well, I am not Shoeless Joe Jackson, but it ain’t so. In the case of the LHC, it isn’t true for a number of reasons, but black holes in general do not “suck.” 
 
This not just a semantic distinction, but one of process and consequence as well. The word “suck” via suction, as in the way vacuum cleaners work, is not how black holes attract matter. In a vacuum cleaner, the fan produces a partial vacuum (really, just a slightly lower pressure) at the floor end of the vacuum, and regular air pressure outside, being greater, pushes the air into it, carrying along loose dirt and dust. 
 
In the case of black holes, there is no suction involved. Instead, matter is pulled into the black hole by a very strong gravitational attraction. In one way of visualizing it, it really is a bit like falling into a hole, but not like being hoovered into it. Gravity is a fundamental force of Nature, and all matter has it. When something is pulled into a black hole, the process is more like being pulled into like a fish being reeled in by an angler, rather than being pushed along like a rafter inexorably being dragged over a waterfall. 
 
The difference may seem trivial, but from a physical standpoint it is fundamental. 
 
So black holes don’t suck, but they are very cool. Actually, they are cold. Very, very cold. But that’s a story for another time. 
 
credit to earthsky.org

10) Every star you see in the night sky is bigger and brighter than our sun Of the 5,000 or so stars brighter than magnitude 6, only a h...

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