The photo on the preceding web page was developed to show that Alpha Centauri is not a star, however really a star system. Of the 3 stars in the system, the dimmest - referred to as Proxima Centauri - is actually the nearest star come the Sun. The two bright stars, referred to as Alpha Centauri A and B kind a close binary system; they space separated by just 23 time the planet - sunlight distance. This is slightly better than the distance between Uranus and also the Sun.

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The Alpha Centauri mechanism is no visible from much of the north hemisphere. The listed below image shows this star system and also other objects close to it in the sky.


Distance Information

Proxima Centauri, the the next star come our own, is still 40,208,000,000,000 kilometres away. (Or about 268,770 AU.) once we talk about the distances to the stars, us no longer use the AU, or huge Unit; commonly, the light year is used. A light year is the street light travels in one year - the is equal to 9.461 x 1012 km. Alpha Centauri A & B are roughly 4.35 light years far from us. Proxima Centauri is slightly closer at 4.25 light years.

How do We Calculate ranges of This Magnitude?

The methods astronomers usage to measure ranges to the stars are pieces of fundamental and energetic work in astronomy with crucial implications for exactly how we understand the Universe roughly us.

one of the most accurate approaches astronomers use to measure distances to stars is dubbed parallax. If you organize your finger in former of her face and also close one eye and look with the other, then switch eyes, you"ll check out your finger seem come "shift " v respect to much more distant objects behind it. This is due to the fact that your eyes room separated indigenous each various other by a couple of inches - so every eye watch the finger in front of girlfriend from a slightly various angle. The amount her finger seems to transition is called its "parallax".

Astronomers have the right to measure parallax by measuring the position of a nearby star really carefully with respect to much more distant stars behind it, then measuring those positions again 6 months later when the planet is on the opposite next of that orbit. If the star is close enough to us, a measurable parallax will be seen: the place of the star relative to the an ext distant elevator stars will have actually shifted. The shift is small - much less than one arcsecond even for the nearest star. (An arcsecond is 1/60 of one arcminute, i m sorry is 1/60 of a degree.) ( the world has much more information on calculating parallax.)


Image Credit: the Universe, NASA/

Why space These distances Important to Astronomers?

Stars are not in reality stationary objects! The Galaxy is rotating, and also the stars space in orbit approximately its center. Not every star moves at the same rate - how quick they orbit have the right to depend on where the star is situated within the Galaxy. Our Sun, being relatively far from the Galactic Center, takes over 200 million year to one the Galaxy once. Few of the stars close to us space moving quicker than us, and some slower. As Phil Plaitt, from bad Astronomy says, " dare on a highway, stars continually pass each other as castle orbit the Galaxy. They adjust positions, slowly, yet measurably."


This animation by Frog absent Observatory reflects the motion of Barnard"s Star across the skies from 1985 to 2005. Barnard"s Star is pull close the sun so rapidly that approximately 11,700 AD, it will certainly be 3.8 light years from the sun - and also thus the the next star come our own! (Garcia-Sanchez, et al, 2001)

Travel Time

The Voyager 1 spacecraft is on an interstellar mission. The is traveling away from the sunlight at a rate of 17.3 km/s. If Voyager to be to travel to Proxima Centauri, in ~ this rate, it would certainly take over 73,000 year to arrive. If we could travel at the speed of light, one impossibility as result of Special Relativity, it would certainly still take 4.22 years to arrive!

Why Can"t us Travel quicker Than the speed Of Light?

According to one-of-a-kind Relativity the massive of an item increases as its speed increases, and approaches infinity together the object"s speed ideologies the rate of light. This means that it would take an infinite amount of energy to accelerate an item to the rate of light.

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There"s no fundamental reason why we can"t acquire as close to the rate of light together we like, detailed we have enough energy. Yet this is probably much in the future.