The nearest star beyond the sun is Alpha Centauri, 4.2 x 1016 meters away. If we received a radio message from the star today, how long ago would it have been sent?

The distance that light travels in a vacuum in one year, approximately 9.46 trillion (9.46 × 1012) kilometers and there are
1000 meters per kilometer so that's 9.46 x 10^15 meters per light year

so
4.2 x 10^16
---------- = 4.44 years
9.46 x 10^15

Actually, that distance is not quite correct. It is 4.2 light years away, or 3.8*10^16 meters. Divide the distance by the speed of light to get the time. The correct answer is 4.2 years, but you will get a lower number if you use the value you quoted.

Recent data indicate your figure for the distance is OK. I got 4.1*10^16 m from more recent sources. Go with Lance's answer.

1. 👍 0
2. 👎 0
3. 👁 256

Similar Questions

1. physics

Even though we have found an earth sized planet around the nearest star Alpha Centauri B, we're not even close to getting there. To see this let's think about the duration of a flight to Alpha Centauri B, which is about 4×1016

asked by anonymous on July 1, 2013
2. science

What star other than the sun is closest to the earth? Proxima Centauri, which is part of the alpha Centauri three-star system

asked by sally on March 28, 2007
3. astro

ProximaCentauriisapproximatelythesamedistancefromEarth(slightly less than 4.3 light years) as Alpha Centauri A, but it has an apparent magnitude of +11.05, compared to Alpha Centauri A’s magnitude of -0.01. How much more

asked by kennisha on September 27, 2014
4. physic

unit of distance used in astronomy is the parsec (pc): 1 pc = 3.26 ly. The distance to the Earth's next-nearest star, α-Centauri, is 1.3 pc. Find the distance d to α-Centauri in light-years and in meters.

asked by joy on January 19, 2018
5. chemistry

nearest star distance of 4.3 light years proxima centauri is the nearest star to our solar system. what is the distance to proxima centauri kilometers? the speed of light in space is 2.998 x10^8 m/s.

asked by help plz on January 30, 2015
6. Physics

The first accurate measurement of the speed of light was made by Roemer in the 17th century. His measurements were based on observations of (a) The timing of the eclipses of the binary stars Alpha and beta Centauri (B) Refraction

asked by Arielle on November 4, 2011
7. physics

In astronomy, distances are often expressed in light-years. One light-year is the distance traveled by light in one year. The distance to Alpha Centauri, the closest star other than our own sun that can be seen by the naked eye,

asked by rick on March 3, 2008
8. Algebra

A light year, the distance light travels in 1 year,is approximately 5.9x10^12 Alpha centauri A,b 4.3 How far in miles is Alpha Centauri A,B. Scientific notation! I thought the answer was 25.37 x10^12

asked by Anonymous on September 12, 2016
9. Physics

If astronauts could travel at v=0.89c, we on Earth would say it takes (4.20/0.890)=4.72 years to reach Alpha Centauri, 4.20 light years away. The astronaut would disagree. (a) How much time passes on the astronaut's clocks? (b)

asked by LUMBA on May 2, 2012
10. Astronomy

Explain the idea of parallaz. The closet star to the Sun, Proxima Centauri, is 4.2 light years away from us. What is its parallax angle?

asked by Kaitlyn on December 12, 2011

More Similar Questions