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| The Sun provides our planet with |
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| warmth, light, and energy |
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| looks at the processes that formed the Earth |
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| how many stars in universe, and do they have anything orbiting? |
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| The number of stars in our universe is vast and unimaginable. Many of these stars have a family of planets orbiting them. Each of these planetary systems is a different age. Some of them are very old, and some of them are very young. |
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| We see that the youngest planets develop around their parent stars in a giant cloud of dust and gas.We see this dust and gas form a giant swirl, like a whirlpool, funneling more and more material into the planet. Over millions of years this dust and gas help the planet grow. |
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| when do planets stop growing? |
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We can draw pictures of each one, and do our best to lay them out in order from youngest to oldest. By doing this, we can get a pretty good idea of how planetary systems develop. We see that the youngest planets develop around their parent stars in a giant cloud of dust and gas.
As the planets get older, we see that they get larger and larger by collecting dust and gas from that cloud. We see this dust and gas form a giant swirl, like a whirlpool, funneling more and more material into the planet. Over millions of years this dust and gas help the planet grow.
In older planetary systems, we see that the parent stars begins to blow stellar winds outward away from the star. These winds blow much of the dust and gas feeding the planets away, which causes the planets to stop growing |
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| As the planets age, they start to cool down, and their surfaces become hard. Eventually some are cool enough to allow liquid water to form, creating oceans, lakes, rivers, and streams. Other planets do not form liquid water because they remain too hot, or the liquid water eventually freezes because the planets become too cold. However, for a very small group of lucky planets, the temperatures remain just right to allow their water to remain a liquid. |
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| do lakes, mountains, rivers change over time? |
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| The mountains, valleys, hills, streams, rivers, and lakes that we see today are always changing. Over millions of years, new mountains form and older mountains get worn away. Lakes form, then disappear. Streams wander through the countryside, cutting deeper and deeper into the ground creating canyons, which eventually erode away. |
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| what is circumf of earth in miles |
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| highest point and lowest point on earth and the difference |
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| mount Everest, and Mariana trench 12 mile diff |
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| how does the sun create energy? |
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| By converting hydrogen into helium, the Sun generates an enormous amount of energy every second of every day |
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| what causes the changing seasons? |
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| The changing seasons are caused by the movements of the Earth. |
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| What are the two important movements of the earth? |
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| The first is the rotation of the Earth around an invisible axis. It takes the Earth about 24 hours to finish one complete rotation. The second important movement that affects the Earth is its revolution around the Sun. One revolution takes 365 ¼ days, or one year. Acting together, these two movements create variations in temperature, weather, and in the seasons. |
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| How far is the earth from the sun, and how long is the travel around the sun? |
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| 92,000 miles and 540,000 miles. |
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| Seasons are created by two very important events – the rotation of the Earth that gives us day and night, and the rotation of the Earth around the sun that gives us our year. Because the sun never changes, only the movement of the Earth creates changes in light and darkness, and in temperature. |
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| Why is it hotter on some areas of earth and colder on others? |
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| The orbit of the Earth around the sun is elliptical (a squashed circle), and the planet does not sit straight up and down. It sits at a tilt. As the Earth moves in its path around our star, there are times a certain part of the planet is closer to the sun. If the axis (the imaginary straight line around which the Earth rotates to make day and night) is pointing toward the sun, that hemisphere can expect summer. If the axis is pointed away from the sun on the Earth’s yearly trip, that half of the planet will see winter. |
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| Seasons change on or around the 21st of four months: June, September, December and March. In the Northern Hemisphere, December begins winter, March brings on spring, June means summer is beginning and September gives autumn weather. In the Southern hemisphere, the opposite is true. December starts summer, March is the beginning of fall, June starts the winter season and September brings spring. |
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| what caused the earth to rotate? |
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the Earth’s spin, or rotation, was caused by forces during its creation. The Earth was formed amidst a giant cloud of dust and gas. Slowly, over many millions of years, this dust and gas slowly condensed under the force of its own gravity, forming a small mass. As the mass grew larger and larger, so did the force of its gravity. As the young Earth’s gravity became more powerful, it began attracting dust and gas towards it at a faster rate. This caused a sort of traffic jam, as these materials raced towards the Earth. What resulted was a giant whirlpool-like swirl of dust and gas. Consider what happens when you drain your bathtub. As the water all tries to rush down the drain at the same time, a circular funne,l or whirlpool, is created.
Eventually as the young Sun became hotter and brighter, the remaining gas and dust found in the Solar System were blown away. The Sun’s powerful stellar winds cleaned out the Solar System, meaning that the Earth could not grow any larger. Even though the swirling cloud of dust and gas are long gone, the Earth continues to rotate to this day, and will continue rotating throughout its entire planetary life |
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| At two points throughout the year, the tilt of the Earth’s axis reaches its maximum angle compared to the Sun, and begins to move back the other direction. This usually happens around June 21st and December 21st. These days are known as solstices. On these solstices, the rays of the Sun shine directly on one of the two Tropics. During the June Solstice the rays of the Sun shine directly on the Tropic of Cancer. During the December Solstice the Sun’s rays shine on the Tropic of Capricorn. |
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| As the Earth moves around its orbit, it reaches two points during the year where the tilt of its axis causes it to be straight relative to the Sun. These days are known as equinoxes. During these equinoxes the rays of the Sun shine directly on the equator. This happens on approximately March 20th and September 22nd. |
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| what causes short and long days |
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| When the northern part of the Earth is tilted toward the sun, days in the Northern Hemisphere of the Earth are longer. The temperature is warmer. Summer comes to that half of the planet. Because they get most of the sun’s light and warmth, the season changes and things begin to grow. The equator (the exact middle of the Earth measuring from top to bottom) is always the hottest area, but even those places warm in the summer. Six months later, when the Earth has revolved half-way around the sun, the North Pole is tilted as far away from the sun as it ever gets. Days are shorter and the temperature is colder. Winter comes. |
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There is one day each year when the Northern pole of the Earth is closest to the sun. That day falls on June 21-22. That day is called the Northern Solstice. On December 21-22, the Southern Solstice, the southern point of the planet is closest to the sun. The Solstices are more commonly called ‘the Summer Solstice’ and ‘the Winter Solstice’, but that can get confusing, since summer and winter fall in different parts of the year, depending on which hemisphere you live in.
Solstice means ‘sun standing.’ To astronomers (people who study the stars) long ago, it appeared that the sun moved around the Earth. On the two days of solstice, they believed that the sun was standing still because the measurement of the sun from the horizon stopped rising and began to fall again. Then, six months later, it happened again. |
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| The second natural method for measuring the passage of time is by watching the phases of our moon. The moon moves through a 28 day cycle. Each time a cycle is completed, we say that it is a New Moon, or a new lunar month. |
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| he Earth was divided into 24 separate time zones. Each time zone is either one hour ahead or one hour behind the time zone in front and behind it. Over the oceans, these time zones are exactly 15 ° of longitude. |
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| In 1918 the United States began a similar policy. Today, most countries around the world observe Daylight Saving Time. Daylight Saving Time usually begins in April and ends in October in the Northern Hemisphere, after which clocks are set back to standard Sun time. |
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Atmosphere, Lithosphere, Hydrosphere
Scientists divide our home planet into three spheres. Each sphere is categorized according to its physical characteristics. These spheres are the Atmosphere, which is made of all the Earth's gases; the Lithosphere, which is made up of all the Earth's physical materials, such as rocks and soil; and the Hydrosphere, which is made up of all the Earth's water. |
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| How old is the sun and earth? |
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The basic timeline of a 4.6 billion year old Earth, with approximate dates:
3.8 billion years of simple cells (prokaryotes),
3.4 billion years of stromatolites demonstrating photosynthesis,
2 billion years of complex cells (eukaryotes),
1 billion years of multicellular life,
600 million years of simple animals,
570 million years of arthropods (ancestors of insects, arachnids and crustaceans),
550 million years of complex animals,
500 million years of fish and proto-amphibians,
475 million years of land plants,
400 million years of insects and seeds,
360 million years of amphibians,
300 million years of reptiles,
200 million years of mammals,
150 million years of birds,
130 million years of flowers,
65 million years since the dinosaurs died out,
2.5 million years since the appearance of the genus Homo,
200,000 years of anatomically modern humans, |
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