- #1
ElectroBurger
- 20
- 1
How do people calculate the distnce between Earth and a star?
No the galaxy (and the local cluster of galaxies) is held together by gravity.ElectroBurger said:But wouldn't these distances between us and the stars change since the universe is expanding?
Not on the timescales we live for!Making several measurements to the same star over time would tell us the rate of accelerated expansion of the universe, correct?
The Hipparchos mission pushed that out to around 200pc ( 650ly) for high accuracy results and further for the 10-20% accuracy measurements.Chronos said:This kind of measurement is accurate for any star within about 20 light years of earth.
ElectroBurger said:you used the measurment of a parsec, exactly how is that defined? I know that a light year is not an SI unit, and the au is, but is the pc?
Scientists use a method called parallax to calculate the distance to stars. This involves measuring the apparent shift in the position of a star when viewed from two different locations on Earth, and using trigonometry to determine the distance based on the angle of the shift.
The accuracy of distance measurements to stars depends on several factors, such as the precision of the instruments used and the distance of the star. Generally, distances to nearby stars can be measured with high accuracy, while distances to more distant stars may have a larger margin of error.
The distance to stars is typically measured in light years (ly) or parsecs (pc). A light year is the distance that light travels in one year, which is equivalent to about 9.46 trillion kilometers. A parsec is a unit of measurement based on parallax and is equivalent to about 3.26 light years.
For stars that are too far for parallax measurements, scientists use other methods such as spectroscopic parallax, which involves analyzing the light spectrum of a star to determine its luminosity and then calculating its distance based on its apparent brightness. Other methods include using standard candles, such as supernovae, which have a known brightness and can be used to calculate distances to other stars.
Yes, the distance to stars can change over time due to their relative movement in the universe. Stars may move closer or farther away from Earth, which can affect their measured distance. Additionally, as our technology and methods for measuring distance improve, the estimated distances to stars may also change.