What are infrared rays?

Infrared Rays

Infrared rays are waves of invisible radiant energy, like the visible waves of sunlight that travel, or radiate from the sun.

Infrared rays the lie outside the visible spectrum at its red end.  These rays are “redder” than the reddest light our eyes can see, so they are called infrared, meaning “below the red.”

Infrared rays are often called “heat rays.”  They are given off by all warm objects.  Infrared (heat) rays radiate from the hot coals in the fire place, as well as from the sun.

Electric lamps called “heat lamps” produce heat with a special healing filament that sends out infrared rays instead of visible light.  Doctors use infrared heat lamps to treat skin disease and to relieve the discomfort of sore muscles.

The name “black light comes from the use of infrared light in photography.  The rays are so penetrating that photographers take pictures in total darkness with films sensitive to infrared rays.

Photo courtesy:  flickr

 

Why does the moon have phases?

Moon Phases

As we watch the moon night after night, it seems to change its shape.  These different appearances are called phases.

The moon’s rotation around the earth causes the phases.

The moon gives off no light of its own.  It reflects the light from the sun.  The sun can light up only one half of the moon at a time.

The phase that we see from the earth at any time depends on how much of the lighted side is turned towards us.

When the moon is between the earth and the sun, its dark side is turned toward the earth.  At this time, the moon is almost invisible.  It is called the new moon.

A thin crescent appears as we begin to see part of the sunlit side.  Each night the crescent gets a little larger.  After a week, it is a half moon.

At full moon, the moon has circled far enough for us to see all the sunlit half.

As it completes its journey around the earth, the moon again passes through all its phases. – Johnny Wonder

Visual source:  quabbinvalleyparanormal

 

What is a milky way?

Milky Way

If you have ever looked at the sky on a clear night, then you have probably seen a milky-looking path of light across the sky.  This is the Milky Way.

It is actually the light from many billions of stars, most of which are too far away to be seen as separate stars.

The huge cluster of stars make up the Milky Way galaxy, the star system in which our sun has its place.

If we could see all of it at ones, the Milky Way galaxy would appear to be a giant spiraling dish with most of the stars in the center and our sun near the edge.

When we look at the Milky Way, we are looking towards the deepest and densest part of the galaxy.

You see so many stars that they look like a misty band of light stretching from one and of the sky to the other.

How many stars are there in the Milky Way?  Some astronomers think there may be as many as 100 billion stars!

Visual source:  charter

What is the earth’s atmosphere?

You and I live at the bottom of a great ocean of air that surrounds the earth and that extends upward for hundreds of miles.  We call it to the atmosphere.

We could not live without it and the oxygen it contains.

It keeps the earth’s temperature from becoming too hot or too cold.  It also keeps out some harmful energy from the sun.

The atmosphere is made up mostly of nitrogen and oxygen.  But theirs are arise small amounts of other gases present, too.

There is always some water vapor and dust in it, too.

The earth holds the atmosphere to it by the pull of gravity, otherwise it would drift off into space.

The atmosphere is made up of different layers.  The bottom one, the troposphere, holds most of the air living things breathe.

The higher above the earth you go, the thinner the atmosphere becomes until it gradually fades into interplanetary space.,

Visual source:  adventures

What makes a rainbow?

Rainbow

The colors in a rainbow are made by sunlight shining through raindrops in the air, which separate the light into the colors of the spectrum.  

A rainbow occurs at the end of a storm, when the sun begins to shine while the air is still filled with raindrops. 

When the sunlight passes through the millions of water drops in just the right way, the white light breaks up and scatters into the many colors of the spectrum. 

If you are looking in the direction of the drops, with the sun at your back, you will see a rainbow of color arched across the sky in beautiful bands of orange, yellow, green and blue, with red at the top of the arch and violet at the bottom. 

The colors bump to each other so that we rarely see more than four active colors in a rainbow. 

A rainbow disappears soon as there are no longer any raindrops.  You can make a rainbow yourself on a sunny day.  Turn the lawn sprinkler on.  Stand with your back to the sun and look at the spray.  You will be able to see a rainbow. – Johnny Wonder 

Visual courtesy:  missouriskies

Why do we have leap years?

Leap Year

LEAP YEAR IS THE YEAR IN EVERY FOUR THAT HAS 366 DAYS INSTEAD OF 365.  THE EXTRA DAY IS ADDED TO FEBRUAY TO MAKE THE CALENDAR YEAR NEARLY THE SAME AS THE SOLAR YEAR. 

Leap year has 365 days, one more day than an ordinary year.  The calendar we use is based on the amount of time it takes the earth to make one revolution around the sun.  this takes about 365 ¼ days. 

For convenience, we ignore the extra one-fourth-day for three years in every four.  After four years, the leftover time adds up to one full day. 

We add this extra day to the calendar, and say that it  has 365 days.  This fourth year is called “leap year”, and the extra day is February 29. 

But the year is not exactly equal to 365 ¼, days either.  It is actually about 11 minutes shorter.  Adding an extra day in leap year makes the average calendar a few minutes too long. 

So, the day is not added in the century years, except those that can be divided by 400.  Thus A.D. 2000 will be a leap year, but 2100 will not, nor was 1900. 

A person born on February 29 can choose his own birthday – either February 28 or March 1. – Johnny Wonder

Why do we have time zones?

Time Zone

Time zones establish a regular sequence of time changes around the world.  All the places in each zone have the same time.  It is called standard time.  Travelers often pass through time zones.  When it is noon in Chicago, for example, nit is 6 o’clock in the evening in London. 

We can understand why time is not the same everywhere, if we think of telling time by the sun.  It is apparent noon when the sun is highest in the sky.  When it is noon in your town, it is also noon everywhere else straight north and straight south of you.  But a difference of only a few miles east or west makes a difference of a minute in sun time. 

When it is noon in one town, it is not yet noon in a town 10 miles west, and it is already past noon in a town a few miles east.  If every town set its clocks exactly by the sun, few places would be on the same time.  For this reason the world has been divided into 24 equal time zones.  All the clocks in a time zone are set at the same time.  Each zone’s time is one hour earlier than that of the zone east of it. – Johnny Wonder

Visual courtesy:  lib.utexas

what keeps the sun shining and how long can it continue to do so?

Shining Sun

The Sun is a huge ball of extremely hot, glowing gases.  It is considered as the star nearest to the Earth.  It’s mass is equivalent to 333,420 earth. 

The surface temperature of the sun is estimated to be between 5 000 oC to 6 000 oC.  Temperature at the core is as high as 14 000 000 oC.  These temperatures are hot enough to dissolve any metal or rock or to change them into gas. Thus, scientists infer that the sun must be a glove of gas. 

It is believe that the heat of the Sun is the result of nuclear fusion.  This is a process whereby elements with small masses combine to form elements with larger masses.  Hydrogen atoms on the Sun combine together to form helium.  When this happens, tremendous amounts of heat and energy are released. 

This nuclear reaction taking place within the Sun is the source of its energy. 

Hydrogen atom is used up in the process of producing energy.  The sun is destroying itself in the process.  Given its total mass, it will take the sun millions of years before it exhausts its hydrogen supply.  Scientists estimate that the Sun will continue shining for about another 5 000 000 years.  It will then gradually expand, becoming a red giant start that will swallow up all the planets, including the earth.  Then, it will compress into a very small star, or the so-called white dwarf.  Then, it will fade out completely and will become a dark, cold body.

Photo courtesy:  ima.dada

Why do sunsets look red?

Beautiful Sunset

During the evening, when the sun is near the horizon we may see a beautiful sunset.  The reds and oranges of a sunset are caused by the filtering action of the sky. 

Sunlight, as we know, is made of many colors.  We can see the colors that make up sunlight when we look at a rainbow.  As sunlight passes through the atmosphere, the different colors are scattered by the air. 

During the day, when the sun is directly overhead, its rays do not have to travel through as much of the atmosphere to reach the earth.  The sunlight is scattered in such a way that we see more of the blue rays.  But at sunset, when the sun is low in the sky, the light rays must travel through much more of the earth’s atmosphere to reach the viewer. 

As a result, the shorter blue rays are soon scattered out and we can see more of the longer orange and red rays of sunlight – and we have a reddish sunset.  The red color of sunrise is caused the same way. 

Photo courtesy:  scienceblogs

What are stars made of?

Bunch of Stars

Stars are formed from gigantic masses of hot glowing gases.  Hydrogen and helium are the most common gases in a star.  In the clearest night sky you might see a few thousand stars with unaided eye.  Every bright star is a sun, like our own sun. 

 

Scientists tell us that a star is a huge glowing ball of hot gases.  It is a kind of gigantic atomic furnace in which the temperature at the center may be as high as several million degrees.  Hydrogen and helium are the most common gases found in a star.  Although they are made up of gases, their centers are so dense and hot that the atoms of gas are constantly colliding and fusing together into new materials. 

 

As the atoms unite, some of their atomic energy is given off i8n the form of heat and light which stream away from the star in all directions.  This is why stars shine.  Scientists can find out all this by using instruments called spectroscopes.  With these instruments they can tell from the light a star gives what the star is made of and how hot it is.

 

Photo courtesy:  atlasoftheuniverse