Wednesday, August 19, 2015

Why does Saturn have rings?

Scientists have ideas about why Saturn has rings, but no one knows for sure.

What are Saturn's rings made of?

Are they solid? Or are they made of many particles dancing in formation around the planet? Four robotic spacecraft from Earth have visited Saturn—Pioneer 11, Voyager 1, Voyager 2, and Cassini. They have revealed many surprising things about Saturn's rings.


The small color differences in Saturn's rings have been enhanced in this picture from Voyager 2 data.



Over 60 bright and dark ringlets show up in this color enhanced image from Voyager 2 data.

The rings are about 400,000 kilometers (240,000 miles) wide. That's the distance from the Earth to the Moon! But the rings are as little as 100 meters (330 feet) thick. They range from particles too tiny to see to "particles" the size of a bus. Scientists think they are icy snowballs or ice covered rocks.

There are actually many rings—maybe 500 to 1000. There are also gaps in the rings. (That's why we put some black rings on our model Saturns.)


The Cassini spacecraft arrived at Saturn in July 2004 and is still there. It is studying Saturn, its rings, and its moons much more thoroughly than the earlier spacecraft could.

Cassini also carried a probe, called Huygens (HOY-guns), that parachuted into the atmosphere of Saturn's giant moon Titan. Huygens sent back amazing information and images from this strange world whose surface we have never seen.

Monday, August 17, 2015

The Solar Cycle


The Solar Cycle

The Sun's core is made of dense, electrically charged gas called plasma. This roiling, boiling plasma generates the Sun's powerful magnetic field. Earth has a magnetic field too. Like Earth's magnetic field, the Sun's magnetic field has a north pole and asouth pole. However, unlike Earth, on the Sun the magnetic field is complicated—you might even say messy!

About every 11 years, the Sun's magnetic field does a flip. In other words, the north pole becomes the south pole, and the south pole becomes the north pole.

The Sun also does something else every 11 years. Its storminess builds up to a maximum, then it settles back down to a minimum. This repeated behavior is called the solar cycle. When the Sun is the most stormy, that's when its magnetic field flips. Scientists are not sure what the storminess has to do with the magnetic field flipping, if anything.





Sunspots

Sunspots are areas of very strong magnetic forces on the Sun's surface. They look darker than their surroundings because they are cooler. Even so, when there are lots of sunspots, the Sun is actually putting out MORE energy than when there are fewer sunspots. During solar maximum, there are the most sunspots, and during solar minimum, the fewest.

Solar Flares

Solar flares happen because of the constantly moving magnetic fields in the Sun's atmosphere. As the Sun approaches solar maximum (the most active part of its 11-year cycle), its magnetic fields become messier and messier. The magnetic fields loop around, and cross over each other, cutting each other off, and reconnecting.

Have you ever tried sprinkling iron filings on a bar magnet? The iron filings line up along the magnetic lines of force. See the picture in the sidebar above.

Similarly, the hot plasma on the Sun's surface is at the mercy of the magnetic lines of force. Sometimes the plasma gets disconnected from the magnetic fields when the fields come together. Then particles in the hot plasma can speed up greatly and send powerful radiation into space. This is a solar flare.

When the solar cycle is at a minimum, active regions are small and rare and solar flares do not occur very often. They occur more often as the Sun gets near the maximum part of its cycle.

Coronal Mass Ejections

Sometimes, the Sun throws off huge amounts of matter. These events are called coronal mass ejections, or CMEs. A CME can release up to 20 billion tons of this material! If that material were rock, it would make a mountain roughly 2-3/4 miles across and almost 1/2 mile high!



The material thrown off by the Sun can travel a million or more miles per hour (500 km/second). Solar flares and CMEs are the biggest, most violent "explosions" in our solar system, releasing the power of around one billion hydrogen bombs!

Fast CMEs occur more often near the peak of the 11-year solar cycle. CMEs can trigger major upsets in Earth's magnetosphere. The Sun can eject matter in any direction, and very few of the CMEs will actually run into Earth.

Thursday, August 13, 2015

Solar System Facts

  • The solar system includes the sun and all the objects that orbit around it due to its gravity. This includes things such as planets, comets, asteroids and meteoroids
  • The Solar System formed around 4.6 billion years ago.
  • There are eight planets in the Solar System. The four inner planets are mercury, venus, earth and mars while the four outer planets are Jupiter, saturn, uranus and neptune.
  • The inner planets (also known as terrestrial planets) are smaller and made mostly of rock and metal.
  • The outer planets (also known as gas giants) are much larger and made mostly of hydrogen, helium and other gases.
  • As of 2008, there are also five dwarf planets: pluto, Ceres, Eris, Makemake & Haumea.
  • There is an asteroid belt which lies between the orbits or Mars and Jupiter, it features a large number of irregular shaped asteroids.
  • For thousands of years humans were unaware of the Solar System and believed that Earth was at the center of the Universe.
  • Astronomers such as Nicolaus Copernicus, Galileo GalileiJohannes Kepler and Isaac Nelson helped develop a new model that explained the movement of the planets with the Sun at the center of the Solar System.
  • The Sun contains 99.86 percent of the Solar System's known mass, with Jupiter and Saturn making up making up most of the rest. The small inner planets which include Mercury, Venus, Earth and Mars make up a very small percentage of the Solar System’s mass.
          

Sunday, August 9, 2015

Facts about the human teeth

  • Teeth are used to help break down food.
  • Humans form 2 sets of teeth over the course of their lives.
  • The first set (sometimes called baby teeth) features 20 teeth.
  • The second set (sometimes called adult teeth) features 32 teeth.
  • Baby teeth are usually replaced by adult teeth between the ages of 6 and 12.
  • Humans have a variety of teeth including molars, premolars, canines and incisors.
  • Incisors help bite pieces from food.
  • Canines help hold and tear food apart.
  • Molars help grind food.
  • Teeth are covered in a hard substance called enamel.
  • Teeth are surrounded by gums.
  • Cavities can damage a tooth if left untreated.
  • Braces are often used to help straighten or align teeth.


         

Wednesday, August 5, 2015

what is it like inside Jupiter ?


If you have ever spent any time at the bottom of the deep end of a pool, you probably noticed that everything around you seemed heavier. Your ears might have hurt a bit and you might have felt your goggles press harder against your face. This is because the deeper you go, the more water there is on top of you. All that water presses against you and you experience more pressure.
If you notice this effect in a relatively shallow swimming pool, imagine how much pressure you would feel at the bottom of the deepest part of the ocean. At the bottom of the Pacific Ocean, you would feel as if there were over 16,000 pounds of force pressing on every square inch of your body! That’s like having the weight of three cars pressing against every square inch of your body. Obviously no human could survive under such conditions—that’s why we’ve had to build incredibly strong submarines to go that deep.
But that kind of pressure is nothing compared to what would be found at the center of the Earth. Think of everything that would be on top of you—oceans, mountains, millions of tons of molten material, an iron core... In theory, you would experience about 53 million pounds (or around 10,000 cars) of pressure on every square inch of your body at that depth.
But as powerful as that may sound, the pressure at the center of Earth is child’s play compared to the pressure at the center of Jupiter. How much weight would each square inch of your body experience there? Potentially over 650 million pounds! That’s nearly 130,000 cars! If you were to stack up all those cars they would rise up 117 miles above Earth—and if you can imagine it, there would be one stack like that for each square inch of your body!

What Happens Under That Much Pressure?

It turns out some pretty crazy things happen under that kind of immense pressure. Jupiter is made up almost entirely of hydrogen. When you think of hydrogen, you probably think of a common, colorless, odorless gas. But under the millions of pounds of pressure found inside Jupiter, the hydrogen gas is compressed so much that it actually changes into a liquid! Even deeper, the pressure is so great that the liquid hydrogen acts like a metal. Scientists call it liquid metallic hydrogen.


At least we are pretty sure that’s what is going on inside Jupiter. The conditions on Jupiter are so extreme that they can’t really be recreated here on Earth. Scientists have been trying for years to create liquid metallic hydrogen. But it is nearly impossible to mimic the interior of Jupiter on Earth for more than a couple millionths of a second.

The Largest Ocean in the Solar System

animation of cars stacked on top of each other

Despite how hard it is to create these conditions here on Earth, Jupiter is so extremely massive that it probably has an entire ocean of liquid metallic hydrogen deep underneath its cloudy exterior. Incredibly, if scientists are right, it would be the largest ocean in our solar system.
An entire ocean of something we can barely produce here on Earth! Turns out pretty crazy things happen when something is surrounded by the weight of 130,000 cars in every direction!