Monday, December 10, 2007

Science Questions for Dr. Perry

Class, here is where you can ask Dr. Perry astronomy questions you'd like answered! It's your very own spot to ask an expert! Proofread your questions carefully before you post!

Dr. Perry was one of the managing astrophysicists who worked on Hubble Space telescope. Retired, he is currently producing a local access cable TV show, "Know Your Sky" for Anne Arundel County. His show's purpose is to provide the amateur star gazer with information about celestial objects visible during each month of the year and how to find them in the night sky. His other expertises include forest and agricultural preservation.

100 comments:

Juan said...

Does the sun need air to burn like fire?

Andre said...

Where do black holes come from?Some of us think they come from two stars coliding.

Audrey said...

how was the ring made around saturn?

Matthew said...

How was the bigstorm formed on jupiter.

Louis said...

are there other things in space like the milky way

Andre said...

Does the telescope on your show look all the way out to the moon?

Andre said...
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Brianna said...

do the planets grow in space? and if they do how and why?

Isabelle said...

are the stars cateragrized by color?.i know that stars are different color and the sun is a star.

Kendall said...

Do you know if any of the flags get knocked off the moon if so could you explain?

Louis said...

how do gravity are form

Andre said...

How did orion get his name?

Andre said...

Do know any other astrophyists?

Colin said...

can any moon be as big as a planet?

Dr. Perry said...

Hello Mrs. Perry’s science class.

As I get my next show ready, I will answer as many of your questions as time permits.
I will use questions which are interesting to a broad audience on my program.
So, keep watching.

Dr. Perry



Juan said...

Does the sun need air to burn like fire?

The Sun does not “burn like a fire.” The heat and light come from nuclear fusion – like what goes on in a hydrogen bomb.

Tue Sep 11, 11:03:00 AM 2007



Andre said...

Where do black holes come from? Some of us think they come from two stars colliding.

Most black holes are formed in two ways:
As a direct result of the gravitational collapse of a massive star, or by collisions between neutron stars.

Tue Sep 11, 02:52:00 PM 2007

Audrey said...

How was the ring made around Saturn?

The most likely theory is that the rings are the result of an icy moon that was shattered by an impact with a comet. Saturn's other moons do show signs of heavy cratering and this may well be the source of the Saturn's rings.

Tue Sep 11, 02:59:00 PM 2007
Matthew said...

How was the big storm formed on Jupiter.

Strong east-west winds in Jupiter's upper atmosphere form belts in Jupiter’s atmosphere. Within these belts and zones are storm systems that have raged for years. The Great Red Spot, a giant spinning storm (looking like a hurricane), has been observed for more than 300 years.
It is a vast storm, spinning like a cyclone. Unlike a low-pressure hurricane, the Red Spot rotates in a counterclockwise direction in the Southern Hemisphere, showing that it is a high-pressure system. Storm winds reach speeds of 270 mph. The Red Spot is the largest known storm in the solar system; 15,400 miles across, it is twice the size of Earth and one-sixth the diameter of Jupiter.


Tue Sep 11, 03:06:00 PM 2007
Louis said...

Are there other things in space like the Milky Way.

The Milky Way is the name of our home galaxy. There are billions of galaxies like the Milky Way in the universe.

Tue Sep 11, 05:31:00 PM 2007
Andre said...

Does the telescope on your show look all the way out to the moon?

Yes, and beyond! But the real question is how well can you see what’s out there. That depends on the size of the main lens or mirror in the telescope. In general, the larger the better.

Wed Sep 12, 12:15:00 PM 2007

Brianna said...

Do the planets grow in space? And if they do how and why?

Planets can “grow” when material in space fall on the planet. All planets are constantly bombarded by meteoric dust. Sometimes larger objects hit a planet. Not long ago, a comet hit Jupiter. However, most of the “growing” happened long ago when the solar system was forming.

Wed Sep 12, 12:25:00 PM 2007
Isabelle said...

Are the stars categorized by color?. I know that stars are different colors and the sun is a star.

Stars have a range of colors, which represent their surface temperatures. In astronomy, the color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature.

Wed Sep 12, 12:28:00 PM 2007
Kendall said...

Do you know if any of the flags get knocked off the moon if so could you explain?

I am not aware of any flags getting “knocked off” the moon. It is unlikely that any natural event (like a meteor hitting the Moon) would have hit a flag hard enough to “knock it off” the Moon without us noticing it.

Wed Sep 12, 12:40:00 PM 2007
Louis said...

how do gravity are form

What is gravity?

Gravity is one of the fundamental forces of nature. No one really understands exactly why, but gravity is a force that pulls objects toward each other. The mass of the objects and distance between the objects affects the strength of the force of gravity. Greater masses attract with more force and the force weakens as the objects get further apart.

Wed Sep 12, 06:01:00 PM 2007
Andre said...

How did Orion get his name?
Orion was a great huntsman of Greek mythology who was placed among the stars as the constellation of Orion. He is described as a great hunter in the ancient Greek epic, the Odyssey, when Ulysses meets him in the underworld.

Andre said...

Do know any other astrophysicists?

Yes, I do and from time to time, they come on my program to tell us about the interesting work they do.


Mon Sep 17, 02:20:00 PM 2007
Colin said...

Can any moon be as big as a planet?

A moon is a natural satellite rotating around a planet. While moons vary in size, each moon is much smaller than its planet. Several moons are larger than the planet Pluto and two moons are larger than the planet Mercury.



Tue Sep 18, 03:23:00 PM 2007

Mrs. Perry said...

Wow class! Everyone is coming up with fascinating questions to ask our resident astrophysicist! I can tell that you are really thinking about your questions and using this space to ask questions that you really want to know! Keep up the outstanding work!

Steven, you asked a great question, but posted it under Calendar Math! Be sure that you post your comments in the correct section of the blog. I’ll ask it for you:

Dr. Perry, Steven wants to know: Why do stars twinkle?

Dr. Perry said...

Dr. Perry, Steven wants to know: Why do stars twinkle?

Fri Sep 21, 06:10:00 PM 2007

Steven

The scientific name for the twinkling of stars is stellar scintillation (or astronomical scintillation).

Stars twinkle when we look from the Earth, because we see them through thick layers of turbulent (moving) air in the Earth's atmosphere. These thick layers of air are like a lens and tend to move the star’s image around. You can see a similar effect when you look down an asphalt road or a railroad track on a hot day. What you see above the road tends to shimmer and dance around.

Cody said...

why did pluto get changed to a dwarf planet??????????????????????1111111111111111.

Dr. Perry said...

Cody said...

Why did Pluto get changed to a dwarf planet?

Astronomers have discovered many other objects very similar to Pluto in size. So, they refined the definition of planets and created a class called Dwarf Planets to include these objects...
And yes, Pluto is among them.

So now, there are three official classes of objects in our Solar System: planets, dwarf planets, and small solar system bodies.

Louis said...
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Louis said...

what is the biggest planet in the whole universe

Louis said...

why does the earth rotate

Louis said...

why does the sun grow larger

Louis said...

what is mass

Louis said...
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Louis said...

how does nuclear fusion form insde a star or is it already in the star

Andre said...

Will the Sun ever disapear?If it does then where will it go after its collapsed?

Louis said...
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Louis said...

did a comet hit earth and wipe out the dinosaurs

Louis said...

why does light travel so fast

Andre said...

What causes global climent changes?Does the sun cause all of this global warming?

Louis said...

what are the diffrent kinds of craters

Louis said...
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Louis said...

how does the moon reflect the sun's light

Louis said...

if the core of the earth is hot why isn't the ground hot

Louis said...

how does the atmosphere stand up when the gravity is pulling down on it

Louis said...

how long is a light year

Louis said...

How far can scientist look into the universe?

Louis said...

how was earth made?

Dr. Perry said...

Louis said...
What is the biggest planet in the whole universe?
Tue Nov 20, 12:18:00 PM 2007

Louis, we can’t speak for the whole Universe, but the largest planet discovered so far is
the planet HAT-P-1. It’s located about 450 light-years from Earth in the constellation Lacerta. This planet is about 1.4 times larger than Jupiter's.


Louis said...
Why does the earth rotate?
Tue Nov 20, 12:19:00 PM 2007

The answer starts with the forces that formed our solar system four and a half billion years ago. As any gas cloud in this universe, the gas cloud from which our solar system was born was whirling or spinning around. When the gravitational force is larger than the gas pressure, the whirling cloud begins to collapse into a pancake shape, with the Sun spinning at the center. The spin of the Sun is determined by the whirling direction of the original gas.
The pancake contains clumps of dense gas and dust. Dust particles in the clumps collide and collect other dust and gas particles, and grow in size. During this process of growth, the spin of each planet is determined by the captured particles. A planet gains spin by capturing the dust and particles, which collide with it. In this way, the spin keeps changing until no more particles and dust are left in the neighborhood. So, the spin direction is determined by these dust and particles, which collide with the planet. We do not know the details of the condition around the clumps from which the planets are formed, and hence we cannot tell the final spin direction.


Louis said...
Why does the sun grow larger?
Tue Nov 20, 12:20:00 PM 2007

At the end of its life, the Sun will start to fuse helium into heavier elements and begin to swell up. After a billion years as a red giant, it will collapse into a white dwarf -- the final end product of a star like ours. It may take a trillion years to cool off completely.


Louis said...
What is mass?
Tue Nov 20, 12:21:00 PM 2007

We use the word mass to talk about how much matter there is in something. (Matter is anything you can touch physically.) On Earth, we weigh things to figure out how much mass there is. The more matter there is, the more something will weigh. Often, the amount of mass something has is related to its size, but not always. A balloon blown up bigger than your head will still have less matter inside it than your head (for most people, anyhow) and therefore less mass.

The difference between mass and weight is that weight is determined by how much something is pulled by gravity. If we are comparing two different things to each other on Earth, they are pulled the same by gravity and so the one with more mass weighs more. However, in space, where the pull of gravity is very small, something can have almost no weight. It still has matter in it, though, so it still has mass.

Louis said...
How does nuclear fusion form inside a star or is it already in the star
Tue Nov 20, 12:26:00 PM 2007

Watch the December program!

A star shines by nuclear fusion between particles at its center.
The force of gravity presses the particles so close together that they can fuse.
This process generates two positrons.
The positrons travel out from the center of the star and soon meet two electrons.
These are identical in size but opposite in charge.
Positrons are antimatter electrons.
When matter meets antimatter, the particles annihilate each other, converting their mass energy into radiation.
This radiation leaves the star as starlight.
Also, protons boil off the surface and travel out as a solar wind.
This stage in a star's life lasts for billions of years.
Our Sun has reached this stage.



Andre said...
Will the Sun ever disappear? If it does then where will it go after it is collapsed?
Tue Nov 20, 12:31:00 PM 2007

As I said in my November program:

The final stage of solar evolution will be the black dwarf stage.

The white dwarf will emit yellow light and then red light in the course of its evolution, drawing from the star's reservoir of thermal energy.
Its nuclei will be packed as tightly as physically possible and no further collapse is possible.
The body is progressively cooling down and finally becomes as cold as the interstellar space around it, emitting no light at all.
As a carbon-oxygen-rich black dwarf it will continue its journey through the galaxy (milky way) and may eventually encounter another giant gas cloud to become involved in the birth of a new star.



Louis said...
Did a comet hit earth and wipe out the dinosaurs
Tue Nov 20, 12:35:00 PM 2007

Watch this month’s program.

The sudden mass extinction of dinosaurs, an event that occurred approximately 65 million years ago, is one of the most intriguing mysteries in paleontology.
The bulk of the evidence now suggests that a 5–15 km wide meteoric fireball hit in the vicinity of the Yucatan Peninsula, creating the 170 km wide Chicxulub Crater and triggering the mass extinction.
Scientists are not certain whether dinosaurs were thriving or declining before the impact event.
Some scientists propose that the meteorite caused a long and unnatural drop in Earth's atmospheric temperature, while others claim that it would have instead created an unusual heat wave.



Louis said...
Why does light travel so fast
Tue Nov 20, 12:36:00 PM 2007

Science tends to be wonderful at answering how the universe works, but is much less successful at answering why it works the way it does. There are a couple of perspectives on why light travels at 186,000 miles per second. One is that it is just a random accident and that the speed of light could be much faster or much slower, but was set that way in the big bang. Another is that there are fundamental physical theories, which force the speed of light to have a particular value.
Einstein figured out that the constancy of the speed of light is a fundamental property of the universe and has important consequences for the nature of space and time. This is where the theory of special relativity originated, and it produces bizarre effects when objects move close to the speed of light.



Andre said...
What causes global climate changes? Does the sun cause all of this global warming?
Tue Nov 20, 12:36:00 PM 2007

Watch this month’s program!

Climate change refers to the variation in the Earth's global climate or in regional climates over time. It describes changes in the variability or average state of the atmosphere over time scales ranging from decades to millions of years.
These changes can be caused by processes internal to the Earth, and external forces like variations in sunlight intensity and, more recently, human activities.



Louis said...
What are the different kinds of craters?
Sat Nov 24, 11:21:00 AM 2007

Craters are roughly circular, excavated holes made by impact events. The circular shape is due to material flying out in all directions as a result of the explosion upon impact, not a result of the impactor having a circular shape (almost no impactors are spherical). Craters are the most common surface features on many solid planets and moons — Mercury and our Moon are covered with craters.

When an impactor strikes the solid surface of a planet, a shock wave spreads out from the site of the impact. The shock wave fractures the rock and excavates a large cavity (much larger than the impactor). The impact sprays material — ejecta — out in all directions. The impactor is shattered into small pieces and may melt or vaporize. Sometimes the force of the impact is great enough to melt some of the local rock. If an impactor is large enough, some of the material pushed toward the edges of the crater will slump back toward the center and the rock beneath the crater will rebound, or push back up, creating a central peak in the crater. The edges of these larger craters also may slump, creating terraces that step down into the crater.

What are the major parts of a crater?

* Floor — The bottom of a crater, either bowl-shaped or flat, usually below the level of the surrounding ground.
* Central peaks — Peaks formed in the central area of the floor of a large crater. For larger craters (typically a few tens of kilometers in diameter) the excavated crater becomes so great that it collapses on itself. Collapse of the material back into the crater pushes up the mound that forms the central peak. At the same time, the rock beneath the crater rebounds, or bounces back up to add to the peak.
* Walls — The interior sides of a crater, usually steep. They may have giant stair-like terraces that are created by slumping of the walls due to gravity.
* Rim — The edge of the crater. It is elevated above the surrounding terrain because it is composed of material pushed up at the edge during excavation.
* Ejecta — Rock material thrown out of the crater area during an impact event. It is distributed outward from the crater's rim onto the planet's surface as debris. It can be loose materials or a blanket of debris surrounding the crater, thinning at the outermost regions.
* Rays — Bright streaks extending away from the crater sometimes for great distances, composed of ejecta material.




Louis said...
What color is the sun is it white or yellow?
Sat Nov 24, 11:28:00 AM 2007

By definition, the sun is yellow in color but a closer examination by the specialists in the field of light and vision reveals that the sun is more white with a slight trace of yellow color. The explanation given by the experts is there are two factors that affect the perception of the color by the human eye. First has something to do with physics and the nature of light coming from object that is being observed and the second has to do with physiology and how the eyes and brains perceive the light.


Louis said...
How does the moon reflect the sun's light?
Sat Nov 24, 11:29:00 AM 2007

The moon is far from the sun, about 93,000,000 miles. The earth is also about 93,000,000 miles from the sun, yet practically all of the light that we see by in the daytime comes from the sun. How does the light make it so far? Well, the earth is very far from the sun, but the sun is also very big (about 1,000,000 miles across). The proportion of the distance of the sun to the size of the sun is about 93 to 1 - about the same as a regular light bulb 18 feet away. So actually, the light has no problem at all making it that far. But how does it reflect off the moon and travel an additional 250,000 to the Earth. The moon receives only about 8% of the amount of sunlight the Earth receives because it is smaller than the Earth (by an approximate factor of 3.5). The moon reflects about 10% percent of the light that it receives from the sun because it has a gray color. White would reflect 100%. This light goes out in many directions. When the moon is full, the Earth intercepts only about .025% of this light. In the end, the earth receives 444,000 times less light from a full moon than it does from the sun.


Louis said. If the core of the earth is hot, why is not the ground hot?
Sat Nov 24, 11:30:00 AM 2007

The surface of the Earth radiates energy (heat) into space (and it also receives energy from the Sun). The ground is “hot” compared to absolute zero. So, the temperature of the Earth’s surface is in equilibrium between the temperature of the core and that of space. That happens to be the comfort zone for life on Earth.

Louis said...
How does the atmosphere stand up when the gravity is pulling down on it?
Sat Nov 24, 11:32:00 AM 2007

Again, it’s equilibrium; the balance between the pull of gravity and the interaction of the molecules in the atmosphere tending to drive them apart keeps the atmosphere in place.



Louis said...
How long is a light year?
Sat Nov 24, 11:33:00 AM 2007

A light year is the distance light travels in one year going at 186,000 miles per second or:

186,000 miles/second * 60 seconds/minute * 60 minutes/hour * 24 hours/day * 365 days/year = 5,865,696,000,000 miles/year

A light year is 5,865,696,000,000 miles (9,460,800,000,000 kilometers).


Louis said...
What is the atmosphere?
Sun Dec 02, 10:50:00 AM 2007

The atmosphere is just a thin layer of gases that surrounds the Earth. It can act many different ways and you need it to survive. Just as there are layers inside the Earth, there are also layers in the atmosphere. The layers interact, heat up, and interact with the top layer of the Earth's crust. Sometimes you feel the atmosphere as a cool breeze. Sometimes it's a really hot and humid day that seems to push on you from all sides.


Louis said...
How far can scientist look into the universe?
Sun Dec 02, 10:52:00 AM 2007

Using a quasar located 12.3 billion light-years away as a beacon; a team of astronomers detected the presence of molecular hydrogen in the farthest system ever, an otherwise invisible galaxy that we observe when the Universe was less than 1.5 billion years old, that is, about 10% of its present age.




Louis said...
How was earth made?
Sun Dec 02, 10:53:00 AM 2007

The Earth was formed 4.6 billion years ago from the same nebula cloud of gas and dust that the Sun and the eight other planets were formed. However, Earth then was very different from Earth now, and it would have been impossible for life to exist on it. In fact, it is only quite recently in the Earth's 4,600,000,000 year long life that life, resembling modern-day life, has been possible, first with the dinosaurs over 200,000,000 years ago and now with humans and other animals. The Earth is still being formed now. It still has a molten center, which causes volcanoes to occasionally erupt, and plates on the surface which are constantly "swimming" meaning that they collide with other plates and cause earthquakes.

Louis said...

Why is the orin's belt so shiny?

Louis said...

What is a equilibrium in a small defenation that I can under stand?

Louis said...

How many planets can you scientest find in a day?

Louis said...

Approxcentmently how much solar system are in the MilkyWay?

Louis said...

Does a impact crater do more damge then a not impact crater or the other way around?

Louis said...

What the diffrence between a planet and a dwarf planet?

Louis said...

How did the universe begin?

Louis said...
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Louis said...

Why does the atmosphere make stuff look hazy past the atmospere?

Louis said...

what are worm holes?

Louis said...

How do worm holes form?

Louis said...

Have scientist found a worm hole yet?

Louis said...

What is the smallest planet that you can find?

Louis said...

What inspire the scientist the most about studing outer space?

Louis said...

What is a magnet feild?

Louis said...

How many magnet fields are there on the sun?

Louis said...
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Louis said...

What do worm holes do?

Louis said...

What is the biggest telescope?

Louis said...

How far can the best telescope look out into space?

Louis said...

What if two blackholes collide?

Louis said...
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Louis said...

Is there a force that is the equal amount of energy as gravity?If so what is it called?

Louis said...

How do you measure gravity?

Louis said...

Why is the earth going faster when around the sun and slower when far from the sun?(or is it the other way around)

Louis said...

Can our sun change into a baalckhole?

Louis said...

Why is the sun hot?

Louis said...

Why can we see stars that are far away?

Louis said...

Who created light year?

Louis said...

Does mass effect how much gravity pulls down on you?

Louis said...

What is light?

Louis said...

Why does the sun give off light?

Dr. Perry said...

Louis said...

Why is the Orion's belt so shiny?

The three stars making up Orion’s belt are approximately 2nd magnitude stars. While they are not the brightest stars in that constellation, they are close together. This makes the belt stand out among the other stars in Orion.

What is equilibrium in a small definition that I can understand?

Watch the January program!

Equilibrium is the condition of a system in which competing influences are balanced.
Now that’s a complicated definition, so here is a simple example
Suppose you and a friend are at the playground riding on the seesaw.
Therefore, when the two of you weigh the same, the system – you, and your friend, sitting at opposite ends of the seesaw – is said to be in equilibrium.

Does an impact crater do more damage than a not impact crater or the other way around?

Impact craters are caused by two celestial bodies impacting each other, such as a meteorite hitting a planet. Non-impact craters -- volcanic craters or caldera -- are usually formed by volcanic activity. Damage caused by such cratering can be extreme although different. It is the amount of energy dissipated in the formation of the crater that will determine the amount of damage. Small craters of either kind will do less damage than large ones.

What is the difference between a planet and a dwarf planet?

The International Astronomical Union (IAU) defined the core difference between a planet and a dwarf planet as whether the celestial object has "cleared the neighborhood around its orbit" - in other words, whether the object is massive enough to wield a gravity that draws in rocks and other debris that may clutter its orbital path. This criterion disqualified Pluto whose egg-shaped orbit overlaps Neptune's.

How did the universe begin?

Watch the January program!

The Universe began with a Big Bang!

The Big Bang is the scientific theory that the universe emerged from an enormously dense and hot state about 13.7 billion years ago.




Why does the atmosphere make stuff look hazy past the atmosphere?

The haze we see in the atmosphere is caused by particles suspended in the air. These particles can be water (fog), or dust particles from pollution volcanic activity, or dust storms.


What are wormholes?

How do wormholes form?

Have scientist found a wormhole yet?

Watch the January program!

Wormholes are solutions to the Einstein field equations for gravity that act as "tunnels" in space-time. The wormhole or “tunnel” has at least two mouths that are connected to a single throat or tube. However, it has never been proved that wormholes exist and there is no experimental evidence for them.


What inspires the scientist the most about studying outer space?

That all depends on the scientist. There are many different fields of study in astronomy.
Some scientists study the Solar System. They are called planetary scientists. Others study the universe. They are cosmologists. Still others study what stars are made of. We call them spectroscopists.


What is a magnet field?

It was basically a force between electric currents: two parallel currents in the same direction attract, in oposite directions, repel. Iron magnets are a very special case.
In nature, magnetic fields are produced in the rarefied gas of space, in the glowing heat of sunspots and in the molten core of the Earth.


What is the biggest telescope?

The Arecibo observatory is the largest single-aperture telescope ever constructed. It is distinguished by its enormous size: the main collecting dish is 305 m in diameter, constructed inside the depression left by a karst sinkhole. The dish is the largest curved focusing dish on Earth, giving Arecibo the largest electromagnetic-wave gathering capacity. This is a radio telescope not an optical telescope.


What if two black holes collide?

Theory predicts that as the black holes draw near, they kick out the surrounding stars in their neighborhood, which initially provided the braking power to bring them together. When the distance between the black holes shrinks to about the size of the solar system, they start to radiate away energy as gravity waves. This then brings the black holes closer and closer, causing them to spin faster and faster, until they eventually collide in an enormous burst of gravitational radiation.


How do you measure gravity?

You can measure the force of gravity on an object (i.e., its weight) by putting it on a scale.

Why is the earth going faster when around the sun and slower when far from the sun (or is it the other way around)?

You are right. The earth goes faster when it’s closer to the sun.
From Kepler’s Second Law: The line joining a planet with the Sun sweeps equal areas in equal times.

Go to this website http://www.walter-fendt.de/ph11e/keplerlaw2.htm for an animation of this effect. Try Halley’s Comet to see this effect best!


Can our sun change into a black hole?

No, only stars more massive than the sun can.


Why is the sun hot?

The Sun produces energy in the form of heat due to the nuclear fusion reactions going on in its interior.

Who created light year?

The light-year is a measure of distance, not time. It is the total distance that a beam of light, moving in a straight line, travels in one year. To obtain an idea of the size of a light-year, take the circumference of the earth (24,900 miles), lay it out in a straight line, multiply the length of the line by 7.5 (the corresponding distance is one light-second), then place 31.6 million similar lines end to end. The resulting distance is almost 6 trillion (6,000,000,000,000) miles!


Does mass effect how much gravity pulls down on you?

Yes, the force of gravity depends on the mass of an object. Every point mass attracts every other point mass by a force pointing along the line intersecting both points. The force is proportional to the product of the two masses and inversely proportional to the square of the distance between the point masses.

Dr. Perry said...

Louis said...

What is light?

Light, or visible light, is electromagnetic radiation of a wavelength that is visible to the human eye (about 400–700 nm). In a scientific context, the word light is sometimes used to refer to the entire electromagnetic spectrum. Light is composed of an elementary particle called a photon.

Light can exhibit properties of both waves and particles. This property is referred to as wave-particle duality. The study of light, known as optics, is an important research area in modern physics.

Louis said...

Why does the sun give off light?

Deep inside the core of the Sun, enough protons can collide into each other with enough speed that they stick together to form a helium nucleus and generate a tremendous amount of energy at the same time. This process is called nuclear fusion. Every second, a star like our Sun converts 4 million tons of its material into heat and light through the process of nuclear fusion.

Louis said...

Can two planet crash into each other and form one planet?

Louis said...

What would happen if a planet crash into the sun?

Louis said...

What would happen if a blackhole gotten too close to the sun what would happen?

Louis said...

If a blackhole sucks a sun in what would happen?

Louis said...

How about if two suns got into the others magent field what would happen?

Louis said...

What if two metor or more crash into each other would it cause such a explosion that it could be heard trillions miles away or what?

Louis said...

What happens when someting s too big to go down the blackhole's mouth?

Louis said...

What is a defenation for a supernova?

Dr. Perry said...

Louis said

What if two meteors or more crash into each other would it cause such an explosion that it could be heard trillions miles away?

If two meteors collided in the Earth’s atmosphere, there would be a shockwave that would be quite loud – depending on the size of the meteors. However, if the collision occurred in space, there would be no sound since sound needs a medium (air in this case) to travel through.



Louis said...
What is a definition of a supernova?

A supernova is one of the most energetic explosive events known. A supernova occurs at the end of a star's lifetime, when its nuclear fuel is exhausted and it is no longer supported by the release of nuclear energy. If the star is particularly massive, then its core will collapse and in so doing will release a huge amount of energy. This will cause a blast wave that ejects the star's envelope into interstellar space. The result of the collapse may be, in some cases, a rapidly rotating neutron star that can be observed many years later as a radio pulsar.

Dr. Perry said...

Here are answers to Louis' questions that Dr. Clark answered.


1) Can two planets crash into each other and form one planet?

Yes, but it is not that simple. If the planets are large (like the Earth), they will experience tidal forces as they get close to each other. Tidal forces occur because the gravitational force due to planet A is different at different points on planet B (and vice-versa). These forces get big enough to rip the planets apart when they get too close. There would also be substantial melting as the planets got close. If the planets miss each other by a small amount (say a couple of planetary diameters), there would still be some melting and tidal breakup, but the planets would swing by each other, although their velocities would be substantially altered. If they made a direct hit (much less likely), much of the planetary material would be thrown off in various directions, but the bulk of the material could coalesce into a new planet.

2) What would happen if a planet crashed into the sun?

The planet would experience tidal forces as it approached the surface of the sun, and there would be substantial melting accompanying the tidal breakup. Eventually, as the planet moved within the sun, complete melting would occur.

3) What would happen if a black hole gotten too close to the sun what would happen?

The sun and black hole would orbit around each other. How strongly it would interact with the sun depends on the size of the black hole and the radius of the orbit. Typically, it would gravitationally attract material from the outer regions of the sun. As this material was slowly drawn into the black hole, an accretion disk would form around the black hole. Much energy in the form of radiation (e.g. x-rays) and gravitational waves would be given off as material got sucked into the black hole. The sun would slowly get smaller and the black hole bigger. But a black hole with a mass of the Sun is not very large (it is only about 3 kilometers in radius).

4) If a black hole sucks a sun in what would happen?

The process of sucking the sun in would resemble the process described above. When enough material is removed from the sun, the nuclear processes powering the star can be changed, and the characteristics of the sun are altered.

5) If two suns got into the others magnetic field what would happen?

The magnetic field of the sun extends for many millions of miles. It gets weaker as the distance from the sun increases. Unless the stars got fairly close together, the interaction of their magnetic fields would not have important effects. There would be effects involving energetic ions, etc.

6) What happens when something is too big to go down the black hole’s mouth?

A black hole does not have a mouth, but it does have an "event horizon". The event horizon is the radius (the Schwarzschild radius) at which material coming into the black hole is forever lost. Before it reaches this point, tidal forces rip it apart. Now black holes come in different sizes. Let's say you could take the Earth and turn it into a black hole. The Schwarzschild radius would be about 9 millimeters. If the Earth encountered such a black hole, it would get torn apart by tidal forces as it got close enough (see question 1). But only material near the event horizon would actually get sucked in.

Louis said...

Why is it that the Bigger the planet the more gravitational pull it has like Jupiter.

Louis said...

What is the oldest age of a blackhole you can find?

Louis said...

How old can a blackhole be?

Louis said...

If you were deduce the size the universe into a earth object what would it be and if you were how big would our earth be and our sun?

Louis said...

What is the oldest star that can be found with your telscope?

Dr. Perry said...

Louis,

I'll talk about the oldest star a bit later but here is something that might interest you.

NASA reports:
WASHINGTON - A powerful stellar explosion detected March 19 by NASA's Swift satellite has shattered the record for the most distant object that could be seen with the naked eye.

The explosion was a gamma ray burst. Most gamma ray bursts occur when massive stars run out of nuclear fuel. Their cores collapse to form black holes or neutron stars, releasing an intense burst of high-energy gamma rays and ejecting particle jets that rip through space at nearly the speed of light like turbocharged cosmic blowtorches. When the jets plow into surrounding interstellar clouds, they heat the gas, often generating bright afterglows. Gamma ray bursts are the most luminous explosions in the universe since the big bang.

Go to: http://www.nasa.gov/centers/goddard/news/topstory/2008/brightest_grb.html

for more details and pictures.

Dr. Perry said...

Here are more answers from Dr. Clark


Do black holes ever die?

Possibly. If the expanding universe eventually contracts and collapses
on itself, all existing black holes should be destroyed. Very small black
holes (none are known to exist) can theoretically lose mass by the
Bekenstein-Hawking process. This process works by creating matter-
antimatter pairs near the event horizon of a black hole. One particle
gets sucked into the black hole, the other escapes. The smaller the
black hole, the more rapid the loss. Larger black holes can also lose
mass from this effect, but the loss is almost negligible.


How are craters on the moon formed?

Craters on the moon are formed by the impact of smaller bodies
(e.g. asteroids and comets). On the moon, these craters last for a
long time. The earth also is impacted by asteroids and comets.
But craters on the earth are quickly eroded by rain, wind and
tectonic forces. There are a few craters on earth recent enough that
they can be visited (like Berringer's Crater near Winslow, AZ).
Some very large old craters can be seen in satellite photos, but
image processing (and a good imagination) is often required.


What happens to things when they are sucked in a black hole?

For black holes of stellar origin (about 4 to 15 solar masses),
tidal forces would rip you apart as you approached the "event
horizon". This horizon is the point of no return. After you pass the
event horizon and approach the center of the black hole, you are
crushed to a very small (zero?) size. We have no way of observing
what happens inside a black hole, because even light cannot get out.


When the sun goes into red giant phase will we all die?

In about 5 billion years, when the sun starts burning helium and enters
the red giant phase, its outer edge will approach the present orbit of the
Earth. The atmosphere will be lost, the oceans will boil (and the resulting
water vapor will be lost), and the remains of the earth will be very hot.
Life (as we know it) will be impossible. But we have 5 billion years to
plan our escape.

What is dark matter?

Dark matter is a hypothetical form of matter that cannot be observed
directly (by emitting radiation of any type), but is inferred by its gravitational
effects. Only about 4% of the "required" total mass (or energy) in the universe is
observable. Current theories say that about 20% of this missing material is in the
form of dark matter. The rest is thought to be in the form of "dark energy". Not too
much is known about either dark matter or dark energy.

What is plasma?

A plasma is a hot, ionized gas. Most of the universe (including all the
stars) is in the plasma state. In an ionized gas, one or more electrons
are stripped away from each atom.

Why is it that the Bigger the planet the more gravitational pull it has like Jupiter.

Matter is attracted gravitationally to other matter. The attraction takes the form

F = G m(1) m(2) / R(1-2)^2

Where F is the force of attraction, G is the gravitational constant, m(1) is the mass
of body 1, m(2) is the mass of body 2, and R(1-2) is the distance between them.
Jupiter is very massive (it is 319 times the mass of the earth and 11 times the radius
of the earth). The gravitational acceleration at a given distance from a planet is directly
proportional to the total mass of the planet. The force decreases with the square of
distance from the center of the planet. The surface of Jupiter is 44000 miles from its
center. At this point, the gravitational acceleration is about 2.64 times the gravitational
acceleration at the earth's surface (4000 miles from the center). At the same distance
as above (44000 miles) the acceleration for earth is 11x11=121 times less. Thus it is
319 times less (11x11x2.64) than the Jupiter case.

Louis said...

Can the Gravitation pull of a bigger star from 1,000 Killometers away come close enough to pull us out of our orbit?

Louis said...

How could we tell that a blackhaole was entering our solar sytem , would we feel right away pull or wait alitte to feel it?

Louis said...

How close can a comet come but miss earth?

Louis said...

When will it take for a astriod to hit earth?

Andre said...

1.) Will the world ever end if so what will it look like and will we be a dwarf planet like pluto?

2.) Will al the other planets become a dwarf planet?

Louis said...

How strong is the strongest gravatational pull of a object in over universe not counting a blackhole?

Louis said...

is there any other object i the whole entire universe that could stastain life on it that is not earth

Louis said...

Where is the closes but also more brighter and bigger than the sun?

Louis said...

How far away does a object need to be so that we can hear it crash into something.