Is the Sun actually a star?
Our Sun is a 4.5 billion-year-old star – a hot glowing ball of hydrogen and helium at the center of our solar system. The Sun is about 93 million miles (150 million kilometers) from Earth, and without its energy, life as we know it could not exist here on our home planet.
In space or on the Moon there is no atmosphere to scatter light. The light from the sun travels a straight line without scattering and all the colors stay together.
In reality, the moon is not considered a star. While it shines just like many of the stars in the sky, its light comes from the sun, not itself. To be a star, a celestial body must be capable of igniting itself because of its mass. The moon's core has never ignited, so it does not fall under the definition of a star.
Sun- the star of our solar system is a star because it produces energy by the fusion reaction of Helium turning into Hydrogen. Our Sun is an average-sized star: there are smaller stars and larger stars, even up to 100 times larger. The Sun is composed almost entirely of hydrogen and helium gas.
Answer. Kat - No it isn't. It is a big flaming ball of exploding helium or hydrogen, one of the two.
Who discovered that the Sun was a star? Many people's work was needed to prove that the Sun is a star. The first person we know of to suggest that the Sun is a star up close (or, conversely, that stars are Suns far away) was Anaxagoras, around 450 BC.
A succession of astronauts have described the smell as '… a rather pleasant metallic sensation ... [like] ... sweet-smelling welding fumes', 'burning metal', 'a distinct odour of ozone, an acrid smell', 'walnuts and brake pads', 'gunpowder' and even 'burnt almond cookie'.
Most of the space is empty, as the gas molecules in space are so few and far from each other that they do not collide regularly with each other, so even when the sun heats them with infrared waves, this heat transfer through conduction is not possible.
Averaged over the whole sky, however, this beige colour is diluted and appears almost, but not quite, black. Given the immense size of the Universe, and the abundance of stars, it might be surprising that the sky isn't bright white.
We only see the Moon because sunlight reflects off of it. As the sunlight that was illuminating the Moon disappears, so would the Moon! The same would go for the many other celestial bodies in the sky, such as planets, which we see only because of the Sun's reflected light.
What holds the sun up in the sky?
The Sun is a huge ball of hydrogen and helium held together by its own gravity.
Unlike stars, planets do not experience nuclear fusion, the process of combining tiny particles called atoms to release energy. Nuclear fusion creates radiation (heat and light) and makes stars glow. Because planets do not have nuclear fusion, they do not produce their own light.
The Sun survives by burning hydrogen atoms into helium atoms in its core. In fact, it burns through 600 million tons of hydrogen every second. And as the Sun's core becomes saturated with this helium, it shrinks, causing nuclear fusion reactions to speed up - which means that the Sun spits out more energy.
The Sun and the planets formed together, 4.6 billion years ago, from a cloud of gas and dust called the solar nebula. A shock wave from a nearby supernova explosion probably initiated the collapse of the solar nebula. The Sun formed in the center, and the planets formed in a thin disk orbiting around it.
At its core, the sun burns millions of tons of hydrogen every second in a process called "nuclear fusion." Fusion turns hydrogen into helium and releases incredible amounts of energy in the process. It's fusion that creates the heat and the rays of light that eventually reach Earth.
Nothing is more important to us on Earth than the Sun. Without the Sun's heat and light, the Earth would be a lifeless ball of ice-coated rock. The Sun warms our seas, stirs our atmosphere, generates our weather patterns, and gives energy to the growing green plants that provide the food and oxygen for life on Earth.
It is just far enough away to keep us from burning. And we get the amount of warmth needed for humans, animals and plants to live. If the sun would go out, no life could survive on most of earth's surface within a few weeks. Water and air would freeze over into sheets of ice.
With no sunlight, photosynthesis would stop, but that would only kill some of the plants—there are some larger trees that can survive for decades without it. Within a few days, however, the temperatures would begin to drop, and any humans left on the planet's surface would die soon after.
So, before the Sun, there must have existed a star - probably an intermediate mass star - which evolved to become a giant, made barium in its interior, then lost its envelope through a massive wind into the interstellar medium, and that material was incorporated into the protosun.
Our Sun is doomed. Billions of years from now, the Sun will deplete its hydrogen fuel and swell to a red giant before becoming a white dwarf. It's a well-known story, and one astronomer has understood it for decades.
How long would it take for us to realize the Sun died?
If the sun disappears suddenly, total darkness will be observed on Earth after 8 minutes – the time it take for its light to reach us.
In space we can assume that there would be no external organisms such as insects and fungi to break down the body, but we still carry plenty of bacteria with us. Left unchecked, these would rapidly multiply and cause putrefaction of a corpse on board the shuttle or the ISS.
No, they don't believe there's an end to space. However, we can only see a certain volume of all that's out there. Since the universe is 13.8 billion years old, light from a galaxy more than 13.8 billion light-years away hasn't had time to reach us yet, so we have no way of knowing such a galaxy exists.
Sound travels through the vibration of atoms and molecules in a medium (such as air or water). In space, where there is no air, sound has no way to travel.
It's also very cold in space. You'll eventually freeze solid. Depending on where you are in space, this will take 12-26 hours, but if you're close to a star, you'll be burnt to a crisp instead.
No, there isn't sound in space.
This is because sound travels through the vibration of particles, and space is a vacuum. On Earth, sound mainly travels to your ears by way of vibrating air molecules, but in near-empty regions of space there are no (or very, very few) particles to vibrate – so no sound.
There's a limit to how much of the universe we can see. The observable universe is finite in that it hasn't existed forever. It extends 46 billion light years in every direction from us. (While our universe is 13.8 billion years old, the observable universe reaches further since the universe is expanding).
The answer: The stars are there, they're just too faint to show up.
In space, no one can hear you scream. This is because there is no air in space – it is a vacuum. Sound waves cannot travel through a vacuum. 'Outer space' begins about 100 km above the Earth, where the shell of air around our planet disappears.
Above the Earth's atmosphere, outer space dims even further, fading to an inky pitch-black. And yet even there, space isn't absolutely black. The universe has a suffused feeble glimmer from innumerable distant stars and galaxies. This artist's illustration shows NASA's New Horizons spacecraft in the outer solar system.
Would the Earth survive if there was no moon?
It is the pull of the Moon's gravity on the Earth that holds our planet in place. Without the Moon stabilising our tilt, it is possible that the Earth's tilt could vary wildly. It would move from no tilt (which means no seasons) to a large tilt (which means extreme weather and even ice ages).
When the Sun exhausts its store of nuclear fuel, some 5 billion years from now, it will evolve into a bloated red giant, gobbling up Mercury and Venus, and scorching the Earth. After ejecting its outer layers in the form of a colourful planetary nebula, the Sun will then be compressed into a tiny white dwarf star.
Eternal night would fall over the planet and Earth will start traveling into interstellar space at 18 miles per second. Within 2 seconds, the full moon reflecting the sun's rays on the dark side of the planet would also go dark.
No asteroids have ever been observed to hit the Sun, but that doesn't mean that they don't! Asteroids are normally content to stay in the asteroid belt between Mars and Jupiter, but occasionally something nudges them out of their original orbits, and they come careening into the inner solar system.
That hasn't happened, so unless beings on a hidden planet have invented both an invisibility cloak and a gravity-masking device, the other side of the sun is almost certainly just empty space.
But if you take a look around, there's nothing here for you to actually land on, because the sun doesn't have any solid surface to speak of. It's just a giant ball of hydrogen and helium gas.
"There could be several billions of these free-floating giant planets roaming freely in the Milky Way without a host star." And finding more of these types of celestial travelers will help scientists understand their origins.
Shooting stars are actually what astronomers call meteors. Most meteors burn up in the atmosphere before they reach the ground. However, once in a while a meteor is large enough than some of it survives and reaches Earth's surface. Then it is called a meteorite.
Stars are born within the clouds of dust and scattered throughout most galaxies. A familiar example of such as a dust cloud is the Orion Nebula. Turbulence deep within these clouds gives rise to knots with sufficient mass that the gas and dust can begin to collapse under its own gravitational attraction.
Fires can't start in space itself because there is no oxygen – or indeed anything else – in a vacuum. Yet inside the confines of spacecraft, and freed from gravity, flames behave in strange and beautiful ways. They burn at cooler temperatures, in unfamiliar shapes and are powered by unusual chemistry.
What is the only thing that can destroy the sun?
In fact, since you've got the power to magically replace stellar cores, you would only need to replace the Sun's core with carbon or oxygen to kill it. It actually doesn't have enough mass to fuse even carbon. As soon as you replaced the Sun's core, it would shut off fusion.
I can't get sunburnt when I'm in or around the water. False. Water offers minimal protection from UV radiation. About 40% of UV radiation can still reach the body 0.5 metres below the water surface.
It still has about 5,000,000,000—five billion—years to go. When those five billion years are up, the Sun will become a red giant. That means the Sun will get bigger and cooler at the same time. When that happens, it will be different than the Sun we know today.
If atoms come to a complete stop, they are at absolute zero. Space is just above that, at an average temperature of 2.7 Kelvin (about minus 455 degrees Fahrenheit).
The sun was born about 4.6 billion years ago. Many scientists think the sun and the rest of the solar system formed from a giant, rotating cloud of gas and dust known as the solar nebula.
The Sun does not "burn", like we think of logs in a fire or paper burning. The Sun glows because it is a very big ball of gas, and a process called nuclear fusion is taking place in its core.
The sun is much hotter than lava. Surface temparature of the sun is 10,000 degrees F, while Lava averages only 2000 degrees F.
The hottest thing that we know of (and have seen) is actually a lot closer than you might think. It's right here on Earth at the Large Hadron Collider (LHC). When they smash gold particles together, for a split second, the temperature reaches 7.2 trillion degrees Fahrenheit. That's hotter than a supernova explosion.
Answer: The Sun does not "burn", like we think of logs in a fire or paper burning. The Sun glows because it is a very big ball of gas, and a process called nuclear fusion is taking place in its core.
A galaxy is full of stars: Our sun is just one of at least a hundred billion stars in our own Milky Way galaxy.
How close could a human get to the sun before burning?
You can get surprisingly close. The sun is about 93 million miles away from Earth, and if we think of that distance as a football field, a person starting at one end zone could get about 95 yards before burning up.
When the Sun exhausts its store of nuclear fuel, some 5 billion years from now, it will evolve into a bloated red giant, gobbling up Mercury and Venus, and scorching the Earth. After ejecting its outer layers in the form of a colourful planetary nebula, the Sun will then be compressed into a tiny white dwarf star.
The Sun survives by burning hydrogen atoms into helium atoms in its core. In fact, it burns through 600 million tons of hydrogen every second. And as the Sun's core becomes saturated with this helium, it shrinks, causing nuclear fusion reactions to speed up - which means that the Sun spits out more energy.
Within a few days, however, the temperatures would begin to drop, and any humans left on the planet's surface would die soon after. Within two months, the ocean's surface would freeze over, but it would take another thousand years for our seas to freeze solid.
Stars like our Sun burn for about nine or 10 billion years. So our Sun is about halfway through its life. But don't worry. It still has about 5,000,000,000—five billion—years to go.
Four billion years from now, the increase in Earth's surface temperature will cause a runaway greenhouse effect, creating conditions more extreme than present-day Venus and heating Earth's surface enough to melt it. By that point, all life on Earth will be extinct.
The trite answer is that both space and time were created at the big bang about 14 billion years ago, so there is nothing beyond the universe. However, much of the universe exists beyond the observable universe, which is maybe about 90 billion light years across.
Our sun is really one big star. And there are billions and billions of stars in our universe.
If we made the most straightforward estimate using today's best technology, we'd state there are 170 billion galaxies in our Universe. But we know more than that, and our modern estimate is even grander: two trillion galaxies.
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