Cool Facts About Stars

Cool  Facts About Stars 

Astronomy is the scientific study of stars, planets and other things in space.

Our “Star” (sun) is a yellow star.

The Sun is 93 million miles away from Earth.  (It takes sunlight 8.5 minutes to reach Earth.)

1,300,000 Earths would fit inside the Sun!  WOW!!

Core:  Center of Sun, hottest part.  Nuclear fusion takes place
.
Convection Zone:  Full of hot gases.  Energy released.

Photosphere:  Source of sunlight.  Visible part of Sun.

Prominences:  Flame-like gases that travel outward
.
Sunspots:  Darker, cooler areas of Sun.

Solar Flares:  Streams of charges atoms.

Corona:  Outer atmosphere.

Chromosphere:  Gases above the photosphere.  Seen only during an eclipse

Stars are separated by vast distances.

Astronomers use units called light years to measure the distance of stars.

A light-year is the distance that light travels in a vacuum in a year.

Proxima Centauri, is the closest star to the sun.
Astronomers have developed various methods of determining the distance of stars.

The change in position of an object with respect to a distant background is called parallax.

As Earth moves in its orbit, astronomers are able to observe stars from two different positions.

Astronomers measure the parallax of nearby stars to determine their distance from Earth

Astronomers classify stars by their color, size, and brightness.  

Other properties of stars are chemical composition and mass.

Color and Temperature-a stars color indicates the temperature of its’ surface.

The hottest stars appear blue
.
The cooler stars appear red.

The spectrum of color in a star is from blues to greens to yellows and reds.

The brightness of a star as viewed from Earth is dependent on many factors such as color intensity and distance.

Apparent Brightness – is the brightness of a star as it appears from Earth.
The apparent brightness decreases as its distance from you increases
.
Absolute Brightness – is how bright a star really is. The absolute brightness is a characteristic of the star and is not dependent on its distance from Earth.

Each star has its own spectrum.

Most stars have a chemical makeup that is similar to the sun, with hydrogen and helium together making up to 96 to 99.9 % of a star’s mass.

A nebula is a large cloud of gas and dust spread out over a large volume of space.
Some nebulas are glowing clouds lit from within by bright stars.

A star is formed when a contacting cloud of gas and dust becomes so dense and hot that nuclear fusion begins.

Adult Stars - A star’s mass determines the star’s place on the main sequence and how long it will stay.

The amount of gas and dust available when a star forms determines the mass of each young star.

The larger the star the more energy produce.

Since blue stars burn brightly, they use up their fuel quickly and are short lived. 

The dwindling supply of fuel in a star’s core leads to the star’s death as a white dwarf, neutron star, or black hole.

Astronomers have determined that more than half of all stars are members of star systems.

There are three basic kinds of star clusters: open clusters, associations, and globular clusters.

Astronomers classify galaxies into four main types: spiral, barred-spiral, elliptical, and irregular.

The observed red shift in the spectra of galaxies shows that the universe is expanding.

Astronomers theorize that the universe came into being in an event called the big bang.

Dark matter can only be detected by observing its gravitational effects on visible matter.



O  B  A  F  G  K  M
Oh     Be    A     Fine  Guy/Girl,  Kiss  Me!

One   Bug   Ate   Five  Green  Killer  Moths

These are two of many mnemonic devices students and astronomers use to remember the proper order of stellar classification; from the hottest blue stars (O-type) to the coldest red stars (M-type).

The Hertsprung-Russell or H-R diagram reveals that about 90% of all stars lie along a smooth diagonal curve called the main sequence with hot, luminous stars in the upper left and cool, dim stars in the lower right. 

Not all stars fall on the main sequence. Stars below the main sequence are called white dwarfs and those above it are called giants.

The rock stars of the universe-they live fast, die young and leave a spectacular-looking corpse! 

B stars are relatively rare, comprising only 0.1% of main sequence stars.

A stars are amongst the most common naked eye stars.

The best known example of a G star is our SUN!

Most common class by number of stars, since 90% of all stars are red dwarfs.

The Earth is tilted on it’s axis 23.5 degrees.
This is why we have seasons

We have night and day because our planet is rotating or spinning!

The Moon is the Earths only natural satellite.

Ancient man feared the moon- Thought it made a person crazy!

Lunar- From the moon. Lunatic- Crazy person.

1609, Galileo was the 1st person to fully examine the moon through a telescope.

Gravitational Pull: 1/6 that of the Earth. Ex) If you weight 100 pounds on the Earth, you would weigh about 16.5 pounds on the moon!

Rotation:  27 1/3 days
Revolution:  27 1/3 days

We can only see one side of the moon from the Earth.  Astonaughts had to orbit the moon in a rocket ship to see what was on the other side.  The reason why we can only see one side of the moon is because the rotation and revolution are the same.

When the Moon gets between the Sun and Earth.  The Moon casts a small shadow on the Earth.

When the Earth gets between the Sun and the Moon.  The Earth casts a shadow on the Moon.
This is how we knew the Earth was round!