Measuring Astronomical Distances

  • Thread starter jay
  • Start date
In summary, there are several methods for measuring astronomical distances, including parallax, standard candles, and redshift. Parallax can measure distances up to about 100 parsecs, while standard candles and redshift can be used for more distant objects. These methods can be used to calibrate and check each other, but the closer the object, the more accurate the measurement.
  • #1
jay
7
0
Hai..
One 'parsec' is the distance from a star which makes an angle of 1''(1/60 of a degree)with the sun and earth(1.5*10^8 km).So by measuring an angle of 1'' we can measure to a maximum of 2 parsec.
But this only about 7 light years and we are speaking of much much bigger astronomical distances.How these are measured.
Thanks...

Jay
 
Astronomy news on Phys.org
  • #2
A second of arc is actually one 1/60 of 1/60 of a degree -- 1/3600 of a degree.

Parallax can actually make measurements all the way out to nearly a hundred parsecs. You just need equipment that is capable of measuring angles in a sub-arcsecond range. An instrument that can only measure an arcsecond resolution would not be very useful, since only one two stars are that close.

Beyond parallax, we can use stars like Cepheid variables to measure distance. Cepheids have a particular relationship between the period of their variation and their total luminosity (how much total energy per unit time the star is producing). If you can measure the period, you can calculate the luminosity. If you know the luminosity (how bright the star is up-close) and the apparent magnitude (how bright the stars is from where we are), you can calculate its distance.

Even beyond that, we can use the redshift of light from distant galaxies to measure their distances. The farther away a galaxy is, the faster it is moving away from us, and the more its light is redshifted.
 
  • #3
V good explanation:smile:
 
  • #4
The different methods for measuring distances (e.g., parallax for "close" stars, standard candles for more distant galaxies, etc.) have overlapping ranges where they can be applied. So each method can be used to calibrate/check the other. I forget the name of this procedure...the "cosmic distance ladder" or something like that.

The closer the object, the better the measurement. The more distant, the more uncertainty.

another good description...
http://www.straightdope.com/mailbag/mstardistance.html
 
Last edited:

What is the purpose of measuring astronomical distances?

The purpose of measuring astronomical distances is to understand the scale and structure of the universe. By accurately measuring the distances between celestial objects, scientists can learn about the size, age, and evolution of the universe.

How do scientists measure astronomical distances?

Scientists use a variety of techniques and instruments to measure astronomical distances. These include parallax measurements, which use the shift in an object's position relative to distant background stars, and standard candles, which use the known brightness of certain objects to calculate their distance.

What are some challenges in measuring astronomical distances?

One of the biggest challenges in measuring astronomical distances is the vast scale of the universe. Many objects are incredibly far away, making it difficult to accurately measure their distance. Additionally, the presence of dust and gas can obscure objects and make it difficult to determine their true distance.

Why is it important to have accurate measurements of astronomical distances?

Accurate measurements of astronomical distances are crucial for understanding the fundamental properties of the universe. They help us to better understand the formation and evolution of galaxies, the expansion of the universe, and the nature of dark matter and dark energy.

How have advancements in technology improved our ability to measure astronomical distances?

Advancements in technology, such as the development of more powerful telescopes and instruments, have greatly improved our ability to measure astronomical distances. These advancements have allowed scientists to make more precise measurements and discover new objects and phenomena in the universe.

Similar threads

  • Astronomy and Astrophysics
Replies
7
Views
1K
  • Astronomy and Astrophysics
Replies
10
Views
2K
  • Astronomy and Astrophysics
Replies
22
Views
3K
  • Astronomy and Astrophysics
Replies
6
Views
2K
  • Astronomy and Astrophysics
Replies
2
Views
1K
  • Astronomy and Astrophysics
Replies
4
Views
2K
Replies
12
Views
1K
  • Astronomy and Astrophysics
Replies
5
Views
926
Replies
2
Views
2K
Back
Top