Learn About Universe SUN Why Do We Study

Learn About Universe

SUN

Why Do We Study the Sun? We look at the sun rising every day. It’s bright, it’s big and it warms us up. Our sun happens to be the brightest object in our universe and naturally we are really curious to know more about it. Our sun gives us light, heat and energy. It may seem that energy comes from other sources such as gasoline and electricity but the ultimate source of energy for the Earth is nothing else but the sun. Without the sun life on Earth would not exist. It would be so cold that no living thing would be able to survive and our planet would be completely frozen.

The sun is a normal star. It is much closer to us than any other star, and by studying the sun, we can therefore learn more about other stars. The better we understand other stars, the more we know about the Milky Way. From there we know more about other galaxies and in the end we learn more about the universe. The sun also plays the role of a big anchor, which creates gravity that keeps our planet and the other planets of the solar system in a small space. If it weren't for the sun, our planet would simply fly off loose into the universe.

Our sun is very dynamic and it changes constantly. It has the largest eruptions in the solar system. These eruptions can be so large that they can reach our planet and cause serious damage by disrupting satellites and other communication devices. Our TV may not work, our cell phones will be down, a high speed train may run loose and if an astronaut happens to be on the moon at the time when the sun erupts, he or she would be in great danger. NASA uses satellites such as the Solar and Heliospheric Observatory (SOHO), to predict these eruptions so that we have a warning of at least 2 -3 days to protect our expensive communication devices during a solar eruption. SOHO is just one of the instruments that NASA uses to help scientists understand our sun better along with other satellites and large observatories on Earth. Here is what all of us should know about the sun.

. YOUR TOP 10 SUN FACTS: 1. The sun is a star. This makes it extremely important for life on Earth. The sun provides us with energy, which brings life on our planet. It defines the seasons, the harvests, and even the sleep patterns of all living creatures on Earth. 2. The sun is the closest star to our planet. Imagine two cars on the road during the night with their headlights on. One car is closer to you and the other one is far away. Which headlights would seem brighter and bigger? That explains why we see the sun so big and bright. It is simply the nearest star to Earth. 3. Remember! The Earth orbits around the sun. 4. The sun is way bigger than the Earth. In fact its radius is 109 times bigger than the radius of the Earth. For those of you who are curious, the sun’s Radius is 696, 000 km and the Earth’s radius is 6, 376 km.

. YOUR TOP 10 SUN FACTS (Continue) 6. The sun is 150 million km (93 million miles) away from the Earth. 7. How old is the sun? Can you imagine 4. 5 billion years? 8. We know that the Earth’s structure consists of different layers. The sun also has layers but unlike the Earth, the sun is entirely gaseous; there is no solid surface. 9. The sun rotates on its axis approximately once every 26 days. The sun is made of gas, which is why its different parts rotate at different speeds. The fastest rotation is around the equator and the slowest rotation is at the sun’s polar regions (more than 30 days). 10. The sun changes. No matter when or where we look at the sun, we will always see something interesting. Scientists observe these changes by watching the sunspots. They increase and decrease on a regular cycle of about 10. 8 years.

Quick Facts about the Sun Topic Data Diameter 1, 391, 940 km Mass 1. 989 x 1030 kg Surface Temperature 6400 K Interior Temperature 15. 6 x 106 K Rotation 25 Days Composition Hydrogen and Helium Magnetic Field Very Large and Active

Planets Of Our Solar System

Mercury

Mercury is a battered and baked planet just larger than Earth's moon. Evidence of heavy bombardment from the chaos of the formation of the solar system is left in the hundreds of craters and resulting lava flows on this small, barren planet. The largest crater is Beethoven at 643 km in diameter and is the largest in the solar system. The largest feature, Caloris Basin, is 1300 km in diameter and was probably caused by an impact from an object larger than 100 km in diameter. Some craters have ice in them even though the planet is so hot because the sun never reaches into the shadows due to the planet's tilt and orbit. With no atmosphere, there is a temperature difference of about 600 degrees between the coldest spots and hottest spots on the planet. Mercury orbits the sun in about 88 Earth days but takes 58 Earth days to rotate once. On this planet a year takes a (Mercury) day and a half!

Quick Facts about Mercury Topic Data Diameter 4879. 4 km Density 5. 43 g/cm 3 Mass 3. 303 x 1023 kg Volume 6. 084 x 1010 km 3 Temperature Range -173° C to 427° C Atmosphere Some Hydrogen, Helium, Oxygen Winds Moons Average Distance from Sun Orbital Period None 57, 910, 000 km 0 Years, 87 Days, 23. 3 Hours Rotation Tilt Rings Composition Magnetic Field 58 Days, 15. 5 Hours 0. 00° None Iron Core, Silicate Surface Slight

Venus

The brightest of all planets, Venus, is also known as the Morning Star and the Evening Star. This planet is about the same size as Earth but is covered with impenetrable clouds of carbon dioxide and sulfur compounds. Radar mapping of the planet shows lots of craters and that 90% of the landforms are volcanic. Venus spins slowly retrograde (backwards west to east) in 243 days and takes about 225 days to orbit the sun. This makes the daytime about 115 days which can raise surface temperatures up to 464° C. In about a month’s time our Moon appears to change shape called Phases. In 1610 Galileo observed phases and size changes of Venus similar to our natural satellite. His discovery of this and Jupiter’s moons led to a dramatic paradigm shift (way of thinking) from an Earth-centered system to a Sun-centered view. The world was no longer fixed in place and the gods no longer ruled.

Quick Facts about Venus Topic Diameter Density Mass Volume Temperature Range Atmosphere Data 12, 104 km 5. 25 g/cm 3 4. 869 x 1024 kg 9. 284 x 1011 km 3 -45° C to 464° C 97% Carbon Dioxide, Nitrogen Winds Moons Average Distance from Sun Orbital Period 350 km/hr None 108, 200, 000 km 0 Years, 224 Days, 16. 8 Hours Rotation (Retrograde) Tilt Rings Composition Magnetic Field 243 Days, 0. 5 Hours 177. 36° None Iron Core, Silicate Surface Slight

Earth

Earth is third planet from the Sun and the fifth largest planet in the solar system. This section covers topics related to our Planet Earth including links to Earth from space. Earth also exists life. Earth (or the Earth) is the third planet from the Sun and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the World, the Blue Planet

Quick Facts about Earth Topic Diameter Density Mass Volume Temperature Range Atmosphere Winds Moons Average Distance from Sun Orbital Period Rotation Tilt Rings Composition Magnetic Field Data 12, 756. 28 km 5. 515 g/cm 3 5. 976 x 1024 kg 1. 087 x 1012 km 3 -69° C to 58° C Mostly Nitrogen and Oxygen 483 km/hr One 149, 597, 870 km 1 Year, 0 Days, 0 Hours 23 Hours 56. 1 Min 23. 45° None Iron Core, Silicate Surface Up to 362000 km from Surface

Mars

Mars has the largest canyon in the solar system. It would reach from Los Angeles to Chicago if it was on Earth! Mars has a very thin atmosphere, mostly carbon dioxide, but dust storms can cover the whole planet for months at a time. About every two years the Earth and Mars come close together. The planet has two moons, Deimos and Phobos. It would take about 6 months for a spacecraft to get to Mars but the crew would have to wait a year and a half before returning. While there are no current plans for a manned mission to Mars you can see some designs at this NASA website, Mars Mission.

Quick Facts about Mars Topic Diameter Density Mass Volume Temperature Range Atmosphere Winds Moons Average Distance from Sun Orbital Period Data 6794. 4 km 3. 94 g/cm 3 6. 421 x 1023 kg 1. 643 x 1011 km 3 -140° C to 20° C Mostly Carbon Dioxide Up to 100 km/hr 2 227, 940, 000 km 1 Years, 320 Days, 18. 2 Hours Rotation Tilt Rings Composition Magnetic Field 1 Days, 0. 67 Hours 25. 19° No Iron Oxides and Silicates Slight

Jupiter

Jupiter takes about 12 years to orbit the sun and rotates in about 10 hours. This short Jupiter "day" is amazing since the planet is roughly 11 Earth diameters wide. Unlike the rocky planets, Jupiter is a ball of dense hydrogen, helium, water, nitrogen and other gases over a tiny rocky core. Powerful winds dominate the atmosphere with criss-crossing jet streams, lightning and huge hurricane-like storms like the Great Red Spot. This storm has been raging for over 300 years and is about 2 Earth diameters wide. The Great Red Spot can be seen on Jupiter along with four moons:

Quick Facts about Jupiter Topic Diameter Density Mass Volume Temperature Range Atmosphere Data 142, 984 km 1. 33 g/cm 3 1. 900 x 1027 kg 1. 377 x 1015 km 3 -163° C to >-121° C Hydrogen, Helium, Methane Winds Moons Average Distance from Sun Orbital Period Rotation Tilt Rings Composition Magnetic Field Up to 150 m/s 60 778, 330, 000 km 11 Years, 315 Days, 1. 1 Hours 0 Days, 9. 925 Hours 3. 13° Yes Hydrogen and Helium Extends 1, 600, 000 km

Saturn

Saturn and some of its moons can be seen in the composite image at left. Four more moons were found in late 2000 and 9 more were discovered recently for a total of 31. Scientists are tracking more objects that may be additional moons.

Quick Facts about Saturn Topic Diameter Density Mass Volume Temperature Range Atmosphere Data 120, 536 km 0. 69 g/cm 3 5. 688 x 1026 kg 8. 183 x 1014 km 3 -191° C to >-130° C Hydrogen, Helium, Methane Winds Moons Average Distance from Sun Up to 400 m/s 31 1, 429, 400, 000 km Orbital Period 29 Years, 167 Days, 6. 7 Hours Rotation Tilt Rings Composition Magnetic Field 0 Days, 10. 233 Hours 25. 33° Yes Hydrogen and Helium Extremely strong

Uranus

The icy planet Uranus is a smaller version of Jupiter and not the small rocky bodies like Earth. It have faint rings and a number of moons. Uranus takes some 84 years to orbit the sun. It rotates on its side and so half the time one pole is toward the sun and then the other making each of the four seasons last about 20 years. The faint bluish color of the planet is because the methane gas in the atmosphere absorbs red light and reflects blue light.

Quick Facts about Uranus Topic Diameter Density Mass Volume Temperature Range Atmosphere Data 51, 118 km 1. 29 g/cm 3 8. 686 x 1025 kg 6. 995 x 1013 km 3 -214° C to >-205° C Hydrogen, Helium, Methane Winds Moons Average Distance from Sun Up to 160 m/s 16 2, 870, 990, 000 km Orbital Period 84 Years, 3 Days, 15. 66 Hours Rotation Tilt Rings Composition Magnetic Field 0 Days, 17. 25 Hours 97. 86° Yes Hydrogen and Helium Extends 15 times planet radius

Neptune

Blue Neptune is one of the solar system's gas giants. Unlike Earth, gas giants are mostly hydrogen, helium, and methane gases. The methane gas on Neptune gives the planet its blue color because the gas absorbs red light and reflects the blue back into space. Although not seen in the image the planet has a set of very faint rings.

Quick Facts about Neptune Topic Data Diameter 49, 572 km Density 1. 64 g/cm 3 Mass 1. 024 x 1026 kg Volume 6. 379 x 1013 km 3 Temperature Range -223° C to >-220° C Atmosphere Hydrogen, Helium, Methane Winds Moons Average Distance from Sun Up to 2400 m/s 13 4, 504, 300, 000 km Orbital Period 164 Years, 288 Days, 13. 0 Hours Rotation Tilt Rings Composition Magnetic Field 0 Days, 16. 11 Hours 28. 31° Yes Hydrogen and Helium Up to 20 times its radius

Our Dwarf Planet

Pluto

Pluto is a small rocky object that lies at the very edge of the solar system. The planet is so far out it takes light from the sun about 5 and one half hours to reach Pluto in contrast to the 8 minutes it takes to reach Earth. Its orbit of about 248 years sometimes takes it inside Neptune’s orbit. Pluto is so cold that nitrogen and oxygen, which we breathe so easily on Earth, become frozen solid. The planet is only about two-thirds the size of our moon and up until recently was the biggest known object in the Kuiper Belt.

Quick Facts about Pluto Topic Diameter Density Mass Volume Temperature Range Atmosphere Winds Moons Average Distance from Sun Orbital Period Data 2320 km 2. 05 g/cm 3 1. 290 x 1022 kg 6. 545 x 109 km 3 -240° C to -218° C Methane Not Measurable Three 5, 913, 520, 000 km 248 Years, 197 Days, 5. 5 Hours Rotation Tilt Rings Composition 6 Days, 9. 25 Hours 122. 52° None Frozen Methane and Other Ices Magnetic Field None

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