How many au to nearest star

It would be a one-way trip that would take these lightsail-powered spacecraft 20 years. Why go such a long way? Well, for one, astronomers have found two planets orbiting Proxima Centauri.

While it's unlikely they would be habitable, boy would they be fun and informative to visit. Not that it would be an easy trip. But Proxima Centauri is only currently the closest star.

The Sun, the Alpha Centauri system, and other nearby stars all move around the Milky Way over time, and they approach and pass each other as they travel.

In another 10, years or so, the closest star will be something else. Indeed, studies of stars' motions show that many other stars may have ventured close to the solar system throughout its history. Community Leaders: Notable Astronomers. By: Richard S. Wright Jr. However, despite Proxima b's size and location, it's unclear from today's telescopes just how habitable the planet might be.

Astronomers need to run more models and do more comparative studies to better understand how habitable the planet might be. As a start, scientists need to be able to look for signs of an atmosphere.

From there, the investigators can extrapolate whether that atmosphere if present allows liquid water to flow on the surface. Even the surface temperature of the planet, which would also affect habitability characteristics, depends on the atmosphere. The planet may also be so close to its star that it is tidally locked, meaning it always shows the same face to its host star, just as the moon shows only one face the near side to Earth.

This arrangement would make one side of the planet very warm and the other very cold unless winds could distribute the heat around the planet. If that stark temperature difference does exist, it would be a severe challenge to any life. And Proxima Centauri's status as a red dwarf also likely reduces habitability. Red dwarfs are unstable stars, particularly when they are young — such stars produce a lot of stellar activity and emit charged particles , which can cause intense radiation on nearby planets.

Some of this radiation can strip molecules off the top of a planet's atmosphere and thin it over time, according to studies led by the NASA Goddard Space Flight Center in Greenbelt, Maryland. Scientists are continuing to study red dwarf stars to better understand the habitability of worlds like Proxima b.

In November , scientists discovered Ross b , another planet in the habitable zone of a red dwarf that is nearly as close to Earth as Proxima Centauri is, but that appears to be a much quieter star. The Alpha Centauri system is not visible from much of the northern hemisphere. The below image shows this star system and other objects near it in the sky. Proxima Centauri, the closest star to our own, is still 40,,,, km away.

Or about , AU. When we talk about the distances to the stars, we no longer use the AU, or Astronomical Unit; commonly, the light year is used. A light year is the distance light travels in one year - it is equal to 9. Proxima Centauri is slightly closer at 4. The methods astronomers use to measure distances to the stars are pieces of fundamental and active work in astronomy with important implications for how we understand the Universe around us.

One of the most accurate methods astronomers use to measure distances to stars is called parallax. If you hold your finger in front of your face and close one eye and look with the other, then switch eyes, you'll see your finger seem to "shift " with respect to more distant objects behind it. This is because your eyes are separated from each other by a few inches - so each eye sees the finger in front of you from a slightly different angle. The amount your finger seems to shift is called its "parallax".

Astronomers can measure parallax by measuring the position of a nearby star very carefully with respect to more distant stars behind it, then measuring those positions again six months later when the Earth is on the opposite side of its orbit.