What is the average distance between two galaxies

Are these two items about right? Your estimate for the average distance between stars is reasonable. Your estimate for the average distance between galaxies is also a good estimate, which agrees with the information given on Physics Stack Exchange to a similar question.

Or, the brightest galaxy in one cluster should have about the same true brightness as the brightest galaxy in another cluster. Edwin Hubble and his co-worker Milton Humason tried a number of ways, mostly related to the magnitude of the brightest galaxies in big clusters.

You should also experiment with different ways of finding relative distances to clusters. But you have it easier than Hubble and Humason did - you have much better data! Question 4 : What would tell Hubble and Humason that one approach was better than another? Because the properties of galaxies vary so widely, you should use the same measure of relative distance for each cluster you examine. Some examples of things that astronomers have tried to find relative distances to clusters are:.

Once you have chosen a measurement of relative distance, you should use it to find how far galaxies are with respect to Earth. Then a galaxy twice as far away as the nearest galaxy will have a relative distance of 2. Repeat to find the normalized relative distances to farther galaxies. If you normalize all galaxy distances so that the nearest galaxy has a relative distance of 1, you will get an accurate picture of how far away each galaxy is.

Now that you have identified some of the ways to determine relative distances to galaxies, you are ready to use these ways to find the relative distances to some real galaxies. The image shows three galaxy clusters in the same area of the sky. Look closely at the image and decide which galaxies belong to which clusters. Make some notes for yourself about which galaxies belong where.

Exercise 10 : Now, find the relative distances to the galaxies you studied in Exercise 9. Open the Navigation Tool window. Use the zoom buttons the magnifying glasses and blue rectangles on the left side of the window to zoom in our out. Click on the NWSE buttons to shift the part of the sky shown in the main window. Then, click the "specObjs" checkbox. The main window will reload with red squares around all galaxies for which the SDSS has measured a spectrum.

Measure one property of each galaxy you see marked by a red square. From your measurement, calculate the relative distance of each galaxy with respect to the closest one which would have a relative distance of 1.

Record your galaxy measurements as a table with the following format: object ID, right ascension, declination, measurement, relative distance. Then, click "Add to Notes" to save each galaxy to your notebook. Launch the Navigation Tool the tool will open in the same window that held the Object Explorer tool.

Exercise 11 : Repeat Exercise 10 for the same clusters using a different measurement. That's why galaxy collisions are quite frequent while stellar collisions are rare to the point of non-existance. Assuming in we have about two trillion galaxies in an observable universe While this is a notional average, it is not the typical distance between nearest-neighbor galaxies. It would be akin to computing the average distance between grains of sand on the beach by assuming that the grains of sand are spread uniformly over the whole earth.

Bear with me as the illustration may be useful for comparison. So, the best way to answer your question might be to look at our own Local Group of galaxies. Around each of these is a clump of much smaller orbiting satellite galaxies. Simple question requires a simple answer! There are 9,, light years on average between galaxies. How we come to that number: The average distance between galaxies is a few megaparsecs. A megaparsec is 1 million parsecs and there are roughly 3.

For study and visualization of 3D structure and distribution of galaxies less than Mpc from Milky Way, we Douglas and I have developed an open source web simulation with many tools to aid analysis: riteshsingh. The code is open source under the MIT license at github. The associated publication is available here: academic. Sign up to join this community.

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