See the map of New York. Wikipedia article: New York. Find out the distance between New York and other cities. Find out the distance between New York and the North Pole, the South Pole, the Equator, the Tropic of Cancer, the Tropic of Capricorn, the Arctic Circle, the Antarctic Circle.
The outer layers begin to expand, cool and shine less brightly. The expanding star is now called a Red Giant. The star expands to a Red Giant, below. Stage 8 - The helium core runs out, and the outer layers drift of away from the core as a gaseous shell, this gas that surrounds the core is called a Planetary Nebula.A Planetary Nebula. (Below, NGC 6543).he outer layers begin to expand, cool and shine less brightly. The expanding star is now called a Red Giant. The star expands to a Red Giant, below. Stage 8 - The helium core runs out, and the outer layers drift of away from the core as a gaseous shell, this gas that surrounds the core is called a Planetary Nebula.
A Star's Size. A star begins its life in a contracting nebula of gas and dust. As the density of the material increases under the influence of gravity, compression heats the material. If the material gets hot enough, hydrogen atoms begin fusing together to form helium atoms, and a star is born. A star will spend most of its life, called the main sequence phase, fusing hydrogen into helium. Click the image to see the animation. It's logical that a large nebula (one with a large amount of mass) will form a large star, and a small nebula will form a small star. However, in addition to a star's initial mass, a star's size also depends on the balance between the inward pull of gravity and the outward push of the energy produced by fusion. The entire sequence of a star's evolution can be described in terms of the changing balance between these two opposing forces.