What is a Pulsar
Monday, February 15, 2010 11:45 AM

A pulsar is a highly magnetrized rotating neutron star. They appear to pulse because they have jets of particles moving almost at the speed of light coming from their magnetic poles. These jets produce powerful beams of light. The magnetic pole is slightly misaligned from the rotational axis line, like the magnetic pole on Earth is not in line with our "true north". Picture holding a flashlight in your hand and rotating your hand around. The beam from the flashlight will appear to pulse as it heads towards you and then it stops as it swings away. We observe the beams of light from pulsars only when they are pointing towards Earth and then they appear to go off as the pulsar's magnetic pole is facing away from Earth. This is called the lighthouse effect. The period of pulses range from 1.4 milliseconds to 8.5 seconds.

Shown below is an artist's concept of a pulsar surrounded by material blown away by the supernova explosion.


Image from http://www.nasaimages.org
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Interesting Facts about a Neutron Star
Monday, February 01, 2010 4:31 PM

I did an earlier post of the Life Cycle of a Star. A neutron star is one possible final phase of a star. It is quite a fascinating object that I thought it deserves its own post.

  • Neutron stars are unbelievably, incredibly dense. They have a mass about 1.5 times that of our Sun but with a diameter of about 12.5 miles!
  • The density of the star has caused the protons and electrons to combine into neutrons, thus giving the stars their name. One teaspoon of its material would weigh over 5 million tons on Earth.
  • The denseness also causes an amazing amount of gravity. The escape velocity from the surface of a neutron stay is about one third the speed of light.
  • The massive gravity of the star warps light. If we could look at a neutron star, we would be able to see more than half of the star at a time as shown by the image.
  • Neutron stars rotate very quickly, some up to several times per second.
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Astronomy Scale Comparisons
Monday, January 25, 2010 1:58 PM

The sizes of some of the objects in space are huge. So huge it is difficult to us to comprehend exactly how large they are. Here are some images that may help show the difference in sizes.











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Life Cycle of a Star
Monday, January 18, 2010 2:59 PM

Protostar

Nebula is a cloud of interstellation gas and dust. The gas is mostly hydrogen and the dust is mostly carbon and silicon. The dust and gas in the cloud are pulled together by gravity and it begins to spin. As the gas spins faster, it heats up and becomes a protostar. More matter is attracted to the protostar and it continues to grow in size, mass, and heat.

Main Sequence

When the temperature at the core of a protostar reaches 27,000,000°F, nuclear fusion starts. The nuclear fusion is taking the hydrogen atoms and smashing them together to form a helium atoms. This releases a tremendous amount of energy. The majority of stars in the universe are main sequence stars, including our Sun, and spend the majority of their lives in this stage. They have achieved a hydrostatic equilibrium, where the forces of gravity trying to collapse the star are balanced by the energy released from the fusion reactions trying to blow the star apart.

Red Giant/Supergiant

Eventually, the hydrogen in the core will be used up. The core will contract but the outer layers, still mostly hydrogen, will expand, cool, and glow red. The expansion of the outer layers dramatically increases the size of the star. Thus they become a Red Giant or a Red Supergiant, depending on their initial starting mass. In the core of the red giant/supergiant, nuclear fusion will continue by converting the helium atoms into carbon. The amount of mass a star has determines which of the following life cycle paths it takes from here.

A Red Giant low mass star moves on to

White Dwarf

After the helium in the core has all be converted into carbon, the core collapses again, and this time the outer layers are expelled into planetary nebula. The core remains as a white dwarf. No further nuclear reactions take place and eventually it will cool so that no light is seen. At that point it would be a black dwarf, but no star in the universe has reached that stage yet.

A Red Supergiant high mass star moves on to

Neutron Star / Black Hole

The more massive stars will continue nuclear fusion converting the carbon into even heavier elements. Eventually it will stop. The force of the core collapsing in on itself will cause the electrical forces between the atoms to overcome the gravity and the star will explode into a supernova. If the star was 1.5 to 3 times the size of our Sun, any remaining mass will collapse into a small, dense neutron star. For stars larger than that, its remaining mass will collapse into a black hoe.



Picture from http://www.seasky.org
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A Simulation of the Known Universe
Monday, December 28, 2009 3:28 PM

This is an AMAZING video that starts on planet Earth and zooms out to show the entire universe and then back again. Nothing demonstrates better how insignificant we are in the scope of things.

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Deepest Known Undersea Volcano Erupts
Monday, December 28, 2009 2:59 PM

The West Mata Volcano sits in the Pacific Ocean between Fiji, Tonga, and Samoa almost 4,000 feet below the ocean's surface. The eruption was first spotted in May as it spewed out boninite lavas that are among the hottest recorded in modern times. The water from the volcano was as acidic as battery acid. This video was obtained by using a remotely operated submarine. The pressure of the sea water at that depth was able to suppress the explosive quality of the eruption and allowed the submarine to get quite close.

Boninite lava was previously only found in extinct volcanoes in samples that were at least a million years old. This eruption is the first time scientists could watch the material being created and witness the molten lava flowing on the ocean floor before it was cooled and hardened by the cold water.

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Interesting Facts about the Milky Way Galaxy
Wednesday, December 23, 2009 12:55 PM
  • Our solar system is located in the Milky Way Galaxy.
  • The Milky Way is a barred spiral galaxy. There are two major arms (the spirals) sweeping out from the central rectangular block of stars (the bar).
  • It is more than 13 billion years old.
  • It is 100,000 light years across but only 1,000 light years thick (similar to a frisbee). The representation of the galaxy on the right is a top view.
  • The name Milky Way comes from the band of white light that can be seen across the night sky which is our view of the galactic plane.
  • There are between 200 billion and 400 billion stars in it. We only see about 0.000003% of it.
  • There is a supermassive black hole at the center of the galaxy.
  • Our galaxy is pretty big and smaller galaxies that pass by get ripped to shreds and their mass is pulled into our galaxy.
  • In about 3 billion years, the Milky Way will collide with our nearest neighboring galaxy, Andromeda, and the two will be merged into one galaxy.
by Amaryllis Place | with no comments
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Interesting Facts About The Sun
Monday, December 21, 2009 11:39 AM
  • The Sun’s gravity is 28 times that of Earth.
  • The Sun is 109 times larger than the Earth.
  • The Sun is 93 million miles away from the Earth. Light from the Sun takes just over 8 minutes to arrive at Earth.
  • The Sun contains more than 99.8% of the total mass of the Solar System
  • The Sun is composed of 74% hydrogen, 24% helium, and 2% heavier trace elements.
  • Nuclear reactions, the fusing of hydrogen and helium molecules, are taking place at the Sun's core due to temperature (about 27 million degrees Fahrenheit) and pressure (340 billion times the pressure at the Earth's atmosphere). The energy and heat that this generates takes a million years to reach the surface.
  • The Sun has existed for about 4 and a half billion years and has burnt up about half of the hydrogen in its core. This leaves the Sun's life expectancy to 5 billion more years, at which time the Sun's elements will swell up and then die off leaving a small white dwarf.
  • Approximately every 11 years, the sun reverses its overall magnetic polarity: its north magnetic pole becomes a south pole, and vice versa. This cycle is called "Solarmax".

Image from NASA - Feb 25, 2007

This image was taken by the STEREO-B spacecraft as it was orbiting the Sun, trailing after the Earth about one million miles behind. The size of the Moon as it crosses in front of the Sun appears much smaller due to the greater distance from the Moon. This photograph is a composite of images taken in four different wavelengths of extreme ultraviolet light.

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Butterflies in Space
Tuesday, December 15, 2009 12:48 PM

NASA/BioServe, Univ. of Colo.

Two kinds of caterpillar larvae arrived at the International Space Station last month - Monarch and Painted Ladies. After completing their pupa stages, the first butterflies emerged as the newest kind of residents on the space station. This is the first time that the colorful insects went through all stages of their development (larva, pupa, butterfly) while in orbit.

On Earth, a newly emerged butterfly's wings take about 3 - 5 minutes to dry. In space it took closer to 15 minutes. Their lifespan on the space station is expected to be about half of what it would be on Earth. One thing is the same: you can see lots of larvae poop floating around in the enclosure.

NASA attempted this same experiment a year ago, but the caterpillars never developed into butterflies due to a bad batch of food.

by Amaryllis Place | with no comments
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Space Missions in the Last 50 Years
Thursday, October 15, 2009 1:29 PM

National Geograhic has mapped close to 200 space explorations missions in the picture below. Most have been to our closest neighbors, Venus and Mars and our Moon.

Click image to view full size.

by Amaryllis Place | with no comments
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A New Ring Discovered Around Saturn
Wednesday, October 07, 2009 1:34 PM
New Ring Around Saturn
Image from NASA
A gigantic ring has recently been discovered around Saturn. Most of the material in the ring starts about 3.7 million miles from the planet and extends about another 7.4 million miles. This thing is HUGE. It is made up of ice and dust particles and is not visible with visible light telescopes. The cool ring particles were detected by an infrared telescope. Phoebe, one of Saturn's moons, orbits within the ring, going in the same direction as the ring. All of the other moons and rings of Saturn orbit in the opposite direction.
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Planet Found that Orbits Its Star Backwards
Friday, August 14, 2009 3:40 PM

A new planet was discovered that orbits its star in the opposite direction of the star's rotation. Normally, as a star is spinning it will cause the nearby debris to start circling the star in the same direction and the debris can form planets. It is likely that this planet was orbiting the star in the expected direction, but a close call with another large body could have been the cause of its direction change. This planet, named WASP-17b, has other interesting properties. It orbits very close to its star, less than one-seventh the distance that is between our Sun and Mercery. It is also about twice the size of Jupiter, but only half its density (similar to a packing peanut).

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Disposable Space Station
Wednesday, July 15, 2009 4:26 PM

The International Space Station (ISS) is a research laboratory being built by a number of space agencies. Construction began in 1998 and is supposed to continue into 2011. It is the largest artificial satellite in orbit around Earth and can be see with the naked eye. ISS is in a very low orbit around Earth, only about 242 miles overhead, and circles the Earth 15 times a day. The cost of building this facility is expected to top out around $100 billion dollars, with the US picking up close to a third of that. Unfortunately, NASA only has funding for the project through 2015. If it doesn't find the money to continue, it plans to "de-orbit" the space station in the early part of 2016. Deorbit does not mean taking it apart and bringing it back down to Earth in pieces. It means changing the orbit so that it crashes into the Pacific Ocean. They estimate 80% of it would burn up in the atmosphere and the remaining 20% of the debris would fall into the ocean in an area the size of Alaska.

They do allow tourists to come visit the station at a bargain price of $25 million each. That seems to be the way to go since they make the astronauts on the station work 55 hours a week.

International Space Station
Photo from nasaimages.org

by Amaryllis Place | with no comments
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Interesting Facts about the Moon
Wednesday, June 24, 2009 6:25 PM
  • Diameter is 1/4 the size of Earth's diameter.
  • Gravity is about 1/6 of Earth's gravity. This is too weak to maintain an atmosphere.
  • The Moon's gravity is still enough to affect the tides on the Earth.
  • The same side of the Moon is always facing Earth because the Moon's rotation is synchonous with its revolution around Earth.
  • The Moon is slowing moving away from Earth about 4 centimeters a year.
  • The footprints left on the surface by astronauts will last at least 10 million years.
  • Temperatures can range from +300° F to -270 F./li>
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Interesting Facts about The Asteroid Belt
Tuesday, June 23, 2009 5:05 PM
  • The Asteroid Belt lies between the orbits of Mars and Jupiter.
  • The asteroids are also called minor planets and are irregularly shaped.
  • A fifth planet could have formed in this region, but Jupiter's massive gravitational pull stops this from happening.
  • The asteriods are composed primarilyy of rock and range in size from dust particles to about 590 miles across.
  • A few asteroids have moons of their own.
  • If all of the asteroids in the belt were lumped together, it would be smaller than Earth's moon.
  • This belt is not like the asteroid fields in movies; these asteroids are very far apart.
  • Ceres, the largest object in this region, now qualifies as a dwarf planet like Pluto.
by Amaryllis Place | with no comments
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