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Here you can watch video lectures on astronomy topics. Watch one of 29 individual playlists, or use the Wikimap to find similar topics.

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Articles related to: Distance to Andromeda  Read article

1. Distances from Cepheid Variables  Read article

Cepheid variables are luminous stars with variations in a range of periods of one to fifty days. The physics of their pulsation is well understood, and empirically for stars with well measured distance by parallax, there’s a well determined relationship between the period of the pulsation and the l...

2. Systematic Errors in Distance  Read article

Random errors are errors which improve with the quality or amount of data, so if we want to beat down random errors to a smaller value we simply acquire more observations or build a larger telescope. Systematic errors in astronomy are insidious, because they do not improve with more data or better ...

3. Andromeda Galaxy  Read article

The Andromeda galaxy was visible and must have been known to prehistoric humans, but it was first recorded in the catalog by the Arab astronomer Al Sufi in 964 A.D. Edwin Hubble used his observations of Cepheid variables in the Andromeda galaxy to settle the debate over the nature of the spiral neb...

4. Resolving the Nebula  Read article

The first step in understanding the nature of the nebulae involve resolving the nebulae. As newer, larger telescopes were built near the beginning of the twentieth century astronomers gained powerful tools to break up the diffuse light of the nebulae into the pinpoint light of many stars. Remember...

5. Local Group  Read article

Let’s explore a region of space centered on the Milky Way galaxy, a cube a million parsecs or a megaparsec on a side. That’s equivalent to three and a quarter million lightyears. We would find a collection of galaxies called the local group. There are two large galaxies in the Local Group, the Mi...

6. Nebulae  Read article

The best way to see the medium between stars is when it’s illuminated by a nearby star. Astronomers call the situation where gas and dust is lit up by a star a nebula; the plural is nebulae. Nebulae can surround young stars and be left over material from their formation, or they can surround old s...

7. Hubble Expansion  Read article

Hubble had previously shown that many of the spiral nebulae were in fact distant systems of stars remote from the Milky Way. He then combined the distances he obtained from the Cepheid variable technique with Slipher’s redshifts and some that he measured himself to produce an amazing new result. I...

8. Distance Indicators  Read article

Any property of a star or galaxy that can be used to measure distance is called a distance indicator. In astronomy the best distance indicators have a clear physical or astrophysical basis and are not purely empirically determined. Within the solar system, the most direct technique possible is rad...

9. Measuring the Hubble Constant  Read article

The Hubble constant sets the current expansion rate of the universe and gives an indication of its size and age. The best currently measured value of the Hubble constant comes from a heroic project done with the Hubble Space Telescope over a number of years. The Hubble Space Telescope project was ...

10. Determining Luminosity  Read article

Luminosity, distance, and apparent brightness are all related by the inverse square law of light. If we measure any two of these quantities we can estimate the third. For example, if two stars have the same apparent brightness but one is known to be three times more distant, say by parallax measur...