Home » Astronomy » Stars: Our Sun, nuclear fusion, constellations

Stars: Our Sun, nuclear fusion, constellations


Our Sun

Sun animation

The birth of a star: Formed from a nebula





Nuclear fusion powers stars



Solar nucleosynthesis




Structure of our sun


Life cycle of a star

nebula -> red giant -> collapse -> nova -> white dwarf -> dead star

nebula -> supergiant -> collapse -> supernova -> neutron star

nebula -> supergiant -> collapse -> supernova -> black hole


With beautiul photos:


Hubble Space telescope




The night sky tonight

The night sky tonight (another source)

List of constellations

Are constellations really groups of stars? (i.e. Stars actually near each other)

Or are constellations really illusions? (i.e. Stars actually are far apart, and only appear to be near each other, when seen from Earth.)

Constellations are an illusion

constellation new jpg

From Earth, stars in a constellation appear to be close to each other.
We tend to think that the stars are all at the same distance from us.
But it’s an illusion! In most cases, the stars of a constellation are located at different distances.
Let’s look at Orion the Hunter. Can you tell which star is the farthest? Which is the closest?
Red-colored Betelgeuse (upper left shoulder) and blue-colored Rigel (lower right leg) are the two brightest stars of Orion.
Yet just because a star is the brightest, doesn’t mean it’s the closest. You can’t tell its distance based on its appearance.
The farthest star in Orion is Alnilam, the middle belt star, at 1,359 LY (light-years, the distance light travels in a year.)
There’s 6 trillion miles in one light-year.
The closest is Bellatrix, the upper right shoulder star, at a distance of 243 LY.


Learning Standards

HS-ESS1-1. Use informational text to explain that the life span of the Sun over approximately 10 billion years is a function of nuclear fusion in its core. Communicate that stars, through nuclear fusion over their life cycle, produce elements from helium to iron and release energy that eventually reaches Earth in the form of radiation.

A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas (2012)

Stars’ radiation of visible light and other forms of energy can be measured and studied to develop explanations about the formation, age, and composition of the universe. Stars go through a sequence of developmental stages—they are formed; evolve in size, mass, and brightness; and eventually burn out. Material from earlier stars that exploded as supernovas is recycled to form younger stars and their planetary systems. The sun is a medium-sized star about halfway through its predicted life span of about 10 billion years.

By the end of grade 12. The star called the sun is changing and will burn out over a life span of approximately 10 billion years. The sun is just one of more than 200 billion stars in the Milky Way galaxy, and the Milky Way is just one of hundreds of billions of galaxies in the universe. The study of stars’ light spectra and brightness is used to identify compositional elements of stars, their movements, and their distances from Earth.

ESS1.B  Some objects in the solar system can be seen with the naked eye. Planets in the night sky change positions and are not always visible from Earth as they orbit the sun. Stars appear in patterns called constellations, which can be used for navigation and appear to move together across the sky because of Earth’s rotation.

Benchmarks: American Association for the Advancement of Science

The patterns of stars in the sky stay the same, although they appear to move across the sky nightly, and different stars can be seen in different seasons. 4A/E1

Stars condensed by gravity out of clouds of molecules of the lightest elements until nuclear fusion of the light elements into heavier ones began to occur. Fusion released great amounts of energy over millions of years. 4A/H2cd



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