Answer: the correct answer is (B) He did not know that interstellar dust made it hard from him to see a large part of the Milky Way's disk.
Explanation:
We live in a dusty Galaxy. Because interstellar dust absorbs the light from stars, Herschel could see only those stars within about 6000 light-years of the Sun.
Answer:
While a body is said to be in motion if it changes its position with respect to immediate surroundings.
A body is said to be in uniform motion if it covers equal distances in equal interval of time.
A body is said to be in non-uniform motion if it covers unequal distances in equal interval of time or vice-versa
2NO2 means that there is 2 oxygen atoms and one nitrogen with two sets of that. So its the third one
Anything less dense than water will float, like oil. Anything more dense than water will sink, like rock.
Answer:
finding Cepheid variable and measuring their periods.
Explanation:
This method is called finding Cepheid variable and measuring their periods.
Cepheid variable is actually a type of star that has a radial pulsation having a varying brightness and diameter. This change in brightness is very well defined having a period and amplitude.
A potent clear link between the luminosity and pulsation period of a Cepheid variable developed Cepheids as an important determinants of cosmic criteria for scaling galactic and extra galactic distances. Henrietta Swan Leavitt revealed this robust feature of conventional Cepheid in 1908 after observing thousands of variable stars in the Magellanic Clouds. This in fact turn, by making comparisons its established luminosity to its measured brightness, allows one to evaluate the distance to the star.
