For most space objects, we use light-years to describe their distance. A light-year is the distance light travels in one Earth year. One light-year is about 6 trillion miles (9 trillion km). That is a 6 with 12 zeros behind it!
A light-year is a measurement of distance and not time (as the name might imply). A light-year is the distance a beam of light travels in a single Earth year, which equates to approximately 6 trillion miles (9.7 trillion kilometers).
The more commonly used light-year is also currently defined to be equal to precisely 31557600 light-seconds, since the definition of a year is based on a Julian year (not the Gregorian year) of exactly 365.25 days, each of exactly 86400 SI seconds.
whence the travel time for 40 light years will be 40×30000016.8≈700000years.
Complete step-by-step solution: The light travels at the speed of 1 light year. Therefore, if we assume light to be travelling, then it will travel 500 light years in 500 years.
As 1 light year is the distance covered by light in one year. So, if the star which is 10 light years away from the earth glows today, then it will be seen after 10 years.
So will it ever be possible for us to travel at light speed? Based on our current understanding of physics and the limits of the natural world, the answer, sadly, is no.
Light can travel at a speed of 300,000 km (186,000 miles) a second. That means that in one second, light travels the distance you would cover if you traveled around Earth 7.5 times! The moon is about one light second away. Let's prove this.
Distance Information
The Milky Way is about 1,000,000,000,000,000,000 km (about 100,000 light years or about 30 kpc) across. The Sun does not lie near the center of our Galaxy. It lies about 8 kpc from the center on what is known as the Orion Arm of the Milky Way.
We're looking back in time the further out we go because it takes time for light to travel to us. So the furthest out we can see is about 46.5 billion light years away, which is crazy, but it also means you can look back into the past and try to figure out how the universe formed, which again, is what cosmologists do.
It's been 13.8 billion years since the Big Bang, which might lead you to expect that the farthest objects we can possibly see are 13.8 billion light-years away. But not only isn't that true, the farthest distance we can see is more than three times as remote: 46.1 billion light-years.
So, to leave our Galaxy, we would have to travel about 500 light-years vertically, or about 25,000 light-years away from the galactic centre.
One such estimate says that there are between 100 and 200 billion galaxies in the observable universe. Other astronomers have tried to estimate the number of 'missed' galaxies in previous studies and come up with a total number of 2 trillion galaxies in the universe.
Universe is a name given to all the matter around us. Our universe is also called the cosmos. It is originally a greek word.
While 1% of anything doesn't sound like much, with light, that's still really fast – close to 7 million miles per hour! At 1% the speed of light, it would take a little over a second to get from Los Angeles to New York. This is more than 10,000 times faster than a commercial jet.
In short, it means that, the moment that light leaves, darkness returns. In this respect,darkness has the same speed as light.
So light is the fastest thing. Nothing can go faster than that. It's kind of like the speed limit of the universe.
Nothing can travel faster than 300,000 kilometers per second (186,000 miles per second). Only massless particles, including photons, which make up light, can travel at that speed. It's impossible to accelerate any material object up to the speed of light because it would take an infinite amount of energy to do so.
The theory of special relativity showed that particles of light, photons, travel through a vacuum at a constant pace of 670,616,629 miles per hour — a speed that's immensely difficult to achieve and impossible to surpass in that environment.
And if you wanted to actually go into orbit around Pluto, you'd need more rockets to lose all that velocity. So how long does it take to get to Pluto? Roughly 9-12 years. You could probably get there faster, but then you'd get less science done, and it probably wouldn't be worth the rush.
Parsec is larger unit of the distance as compare to the light year. Thus, parsec is the larger unit of the distance than light year and one parsec is approximately times bigger than light year.
Proxima Centauri (Alpha Centauri C)
At 4.2 light-years from Earth, Proxima Centauri is the closest star to our planet other than the sun.
Cosmologists aren't sure if the universe is infinitely big or just extremely large. To measure the universe, astronomers instead look at its curvature. The geometric curve on large scales of the universe tells us about its overall shape. If the universe is perfectly geometrically flat, then it can be infinite.
Earth is in the second largest galaxy of the Local Group - a galaxy called the Milky Way. The Milky Way is a large spiral galaxy. Earth is located in one of the spiral arms of the Milky Way (called the Orion Arm) which lies about two-thirds of the way out from the center of the Galaxy.