One good way to prove the existance of Dark Matter is by calculating the mass required of an immense object to exert on other objects that are visible.

For example, it is possible to calculate the mass of a Sun based on the velocity and distance of its orbiting planets. This is simply calculated using the equation below:

compliments of NASA-CHANDRA X-Ray Observatory

G is the gravitional constant

M is the mass of the object exerting gravitational force (i.e Sun or Galaxy)

r is the radius of the planet from the star

v is the velocity of the planet around the star

By simply solving for M we get M=rv2/G.

This means we can calculate the Mass (of Sun or Galaxy) that is required to achieve the velocity of objects that we see at a radius r.

This simple tool can be used in the same way to determine the Mass of a galaxy required to achieve the velocity of stars around its center.

Astronomers apply this equation to galaxies and use the velocities of stars at the outer edges (v) at a radius (r) to determine the Mass required to achieve these observations.

When astronomers use this equation for galaxies, they come up with a Mass that is significantly LARGER than the existing galaxy, and not just a bit larger, they get a mass of approximately 100X LARGER.

This is extremely puzzling and suggests there is a mass present which does not absorb, reflect or interact with any type of light that astronomers currently use (visible, x-ray, gamma ray, infra-red, radio, micro-wave etc) and therefore cannot be seen.

While it cannot be seen, its gravitational effects on observable objects can be calculated and that's how astronomers know it's there.

Dark matter is estimated to represent about 25% of all mass in the universe while everything visible represents only about 5%. Dark energy represents about 70% of the universe.

It is only through solving the great mystery of dark matter and energy that humans will come to understand the true universe.

Al Maddalena

Maddalena Environmental Inc.

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This is a great video describing the evidence for dark matter and darrk energy, courtesy of History Channel.

1st Evidence for dark matter -Astronomers expected stars near the center of galaxies should travel slower than stars near the outer areas.  What astronomers noticed  was quite different.

Astronomers noticed that velocities of matter in galaxies rotates at the same velocity, no matter where anything is located. There must be matter present exerting a force on all stars in the galaxies that keeps them travelling at the same speed.

2nd Evidence - gravitational lensing.

Astronomers noticed that light from distant galaxies is bent by the gravity of something with immense mass. The bending of light created lensed, duplicate images of those distant galaxies. Visible matter was calculated to be vastly insufficient to bend light of these distant galaxies.  Therefore there must be an immense mass creating the distortion of light from distant galaxies. That something is dark matter. 

Dark matter does not react with any type of light so it cannot be seen. We only know it is there because we can see the effects of its gravity.

It is estimated that 70% of the universe is composed of dark energy, 25% dark matter and only 5% is composed of everything we can see!

We will never completely understand our universe until we understand dark matter and dark energy.

Al Maddalena

Maddalena Environmental Inc.

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Astronomers have known for a long time that the universe is expanding from the initial Big Bang. They had 3 models for expansion: the universe would continue to expand forever, the universe would expand and then slow to a stop, the universe would slow, stop, and then retract, into a huge collapse initiating another Big Bang.

Along comes the Hubble Space Telescope, to change all that. From Hubble, astronomers viewed things in the universe that completely surprised them. They witnessed galaxies that are moving away from one another, in other words, the universe is expanding, but they determined that the universe expansion is speeding up, not slowing down.

This was completely unexpected, because our knowledge of gravity suggests that large objects in the universe should "attract" one another.  The observations of galaxies expanding at a greater rate now as compared to billions of years ago, suggests there is something else out there that is causing this increased rate of expansion.

Thate "something" is dark matter and dark energy.  The term dark is used because we cannot see it using ANY light. It does not reflect, does not refract, does not absorb light of any wavelength (visible light, infra-red, X-rays, gamma rays, ultraviolet light and radio waves).

These lights are the only tools of the astronomer, so if something does not interact with any of these types of light, it cannot be seen!

However, the Hubble Space telescope provided astronomers with something never seen before, but was actually predicted by Einstein.

You see, Einstein predicted that the immense gravity of very large objects in space actually warp space and time, but they also bend light! This is shown by images produced by Hubble (below) compliments of NASA.

Light from distant galaxies is "reflected" by other immense objects that are in the "direct line of sight" producing additional images of these distant galaxies. These images are the result of the bending of the distant light and this bending is called gravitational lensing. Something very massive is bending light from entire galaxies and that something is theorized to be dark matter.

Through gravitational lensing Hubble sees 2 images for the distant galaxy. The immense red "cloud" surrounding the galaxy cluster is thought to be dark matter which bends the distant light. The bending of light into these additional images is called gravitational lensing, and that is how astronomers know that dark matter exists.

Al Maddalena

Maddalena Environmental Inc.

PS. If you're trying to make money online and have had little success so far, you should check out THE EASIEST WAY TO MAKE MONEY ONLINE.

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Carl Sagan, the famous astronomer said it first and was right."We are made of star stuff". In his video, Carl Sagan descibes evolution. We know that Carl Sagan was right because when astronomers point their telescopes at the stars and use a prism to break down light it separates the light into different colours, but more importantly, each element being fused within the star, absorbs the light at different wavelengths.

These absorption lines appear as vertical lines between the colours of the spectra and are different for each element.  This is illustrated below. 

compliments of spiff.rit.edu

So when these light spectra are coming from stars, astronomers know which elements are being fused in each star.  This gives each star a particular signature of elements.

The thing is, no matter where astronomers point their telescopes the variety of elements that are interpreted, the same 92 elements of the Periodic Table are revealed.

Material is spread throughout the universe via supernova explosions of dead stars, which recombine and recycle this matter into new stars which explode again.

This simple and amazing fact indicates that the mass of all the stars in the universe are made of the same star material that we find on Earth. 

As all life on Earth is carbon-based, we are also made of the same material.

Listen to Neil DeGrasse Tyson expalin this.

So you see, Carl was right.

"We are all made of Star Stuff".

Maddalena Environmental Inc.

Al Maddalena

P.S. If you're trying to make money online and have had limited success so far, you should check out the EASIEST WAY TO MAKE MONEY ONLINE.

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Ever wonder how astronomers know the composition of distant stars, galaxies and nebulas? It's easily done by breaking down the light from these distant objects using a prism. Different elements produce different sprectra, so star light can be broken down too.

Here is a video that explains how we know the composition of every star and galaxy at which we can point a telescope.

Here is a great vdeo from Dr. Brian Cox who explains how different elements give off different light spectra and absorption spectra. It is the dark bands of absorption spectra that are the codes for the elements being fused in each star.

By interpreting light sprectra from all the stars in the sky, astronomers have determined that they all contain the same 92 elements found on Earth!

In other words, we are all made of the same "Star Stuff". This links the Earth and all life as we know it, to the rest of the universe.

Astronomers can also use light spectra to determine a star's temperature, distance and they can tell if it is moving away from Earth or moving towards us.

This is light physics at its best.

Maddalena Environmental Inc.

Al Maddalena

P.S. If you're trying to make money online and have had minimal success so far, check out the EASIEST WAY TO MAKE MONEY ONLINE.

Watch a FREE hangout here.

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