Saturn's Rings and Enceladus

We all know Saturn as the big outer planet with the rings. Why does Saturn have such beautiful ring structure? Astronomers aren't entirely sure, but they must have formed back when Saturn was just an infant planet. Astronomers can, however, explain the existence of Saturn's outermost ring, the E ring. Where did this ring come from? The culprit is Saturn's Moon Enceladus!

Above is a recent image taken by the Cassini spacecraft which is currently orbiting Saturn and its moons. As you can see, there appears to be some material erupting from the surface of the moon, and indeed there is! Enceladus experiences what we call cryovolcanism, which means that it has volcanoes which spew water and ammonia when they erupt instead of hot rocky lava. These eruptions are so intense that the material actually leaves the planet and travels into outer space! Since Saturn's rings are so close to Enceladus, the water and other molecules get caught up in Saturn's gravitational field and form the outermost ring. This ring is technically unstable, which means the material will stay for a short time, but then be lost forever into space. That's no big deal though, because Enceladus is continually erupting and adding new material to the E ring.
Image credit: NASA/JPL-Caltech/Space Science Institute

Neutrinos Break the Speed Limit!

 It's by far the hottest news in physics and astronomy right now: neutrinos were found to move faster than the speed of light!

What are neutrinos and where do they come from?

Neutrinos are a subatomic particles. They are essentially the building blocks of atomic particles such as protons and neutrons which are inside atoms. Neutrinos come in different types (or flavors as particle physicists call it) and are often the result of nuclear reactions or radioactive decay of an atom. They are created in stars and supernova explosions, and we can also create them here on Earth using particle accelerator labs. Neutrinos are electrically neutral which means that they don't interact with things often and can therefore travel far distances and through thick objects without ever being bothered. As an example, the sun creates so many neutrinos that every square cm of our body is being hit with 65 billion neutrinos every second! That's right every second! And we never feel anything.

How do you measure the speed of neutrinos?

The first task at hand is to build a device that can detect neutrinos. It's very hard to stop a neutrino, but particle physicists have figured out a way to detect there presence. I'm not going to go into the details here, so you'll just have to take my word for it. The next task is measuring their speed, and that theory is simple. Velocity, or speed in a given direction, can be calculated by taking the distance traveled and dividing by the time it took to move that distance. It's the same concept as driving a car. The distance from point A to point B, divided by the time I took to get there, gives me my average traveling speed in miles per hour. Now imagine a very long underground vacuum tube like the one particle physicists have at CERN. Neutrinos are created at point A at a given time, travel down the tube, and are detected at point B some amount of time later. We know how long the tube is, and we know the departure and arrival time of the neutrinos, so we can calculate a speed!

Faster than light?

Assuming that neutrinos travel at the speed of light (which is the current theory), particle physicists knew how long it should take for the neutrinos to get form point A to point B. When they looked at the timestamps given by the computers, the neutrinos actually arrived at point B ~60 nanoseconds too early! (That's 0.000000060 seconds) This implies that they traveled faster than the speed of light! (By a very tiny amount, but still measurable). The team that conducted the experiment has been checking for any possible errors that they may have made, and have yet to find any.

If no mistakes were made, what does this mean?

Attempting to interpret this result has some pretty cool implications in the world of physics. What does it mean if a neutrino travels faster than the speed of light? Well it sort of means that the neutrino traveled backwards in time! Our sense of time is defined around the speed of light, so if something moves faster than light, it can be observed before it even occurs. Very weird to think about! Another option is that the neutrinos took "short cuts" through higher dimensions during their travels. In this sense, the neutrinos didn't travel faster than light, they just took a shorter path from point A to B that we as humans can not perceive. The final option is that certain parts of the theory of relativity are incorrect and objects can move faster than the speed of light, without traveling back in time or entering different dimensions. Which one of these solutions is right? Well we will have to wait for the next Einstein to come along and figure it out!

The Speed of Light

One of the first things you learn in physics or astronomy 101 is that the speed of light is a constant. We call it by the letter "c", and it's equal to 299,792,458 meters/second or 670,616,629 mph. According to the theory of relativity, nothing can travel faster than the speed of light. Why? It's not something Einstein made up, it comes from the theory of physics. Light has properties of both particles and waves. It tends to travel like a wave (similar to a sound wave), but interacts like a particle (like two objects bumping into each other). The crucial piece to all of this is that light has no weight. It can interact with objects, and it has energy, but no weight. So what does this have to do with speed? Physics says that as you move faster, your mass (how "heavy" you are in a sense) increases. Now I don't mean speeding up from 0 to 60mph in a car, I mean traveling very close to the speed of light. The closer you get to c, the "heavier" you get. If a person were to travel at the speed of light, their mass would be infinity. This is why people, or other massive objects, can't travel at light speed. But since light waves/particles have no mass, they can travel at the speed of light no problem! Experiments show us that light has no mass, and travels a given speed "c". Therefore, any object with zero mass can travel at a maximum speed of c. And since objects can not have negative mass, there is no physical way for anything to travel faster than c. Or is there?.... Tune in later this week to learn about objects called neutrinos that may somehow have the ability to travel faster than the speed of light!

UARS has landed!

You're safe! UARS landed around midnight EST. The map above shows the path the satellite mostly likely took before it hit the ground early this morning.  NASA is still unsure about exactly where it hit, but speculates it was somewhere in the ocean along the green path above since no one reported seeing the crash.

UARS crash landing

 

 Images of UARS tumbling through the atmosphere

Have you heard on the news lately about a NASA satellite that's crashing to Earth this Friday? This object is called the Upper Atmosphere Research Satellite (UARS). It was put into orbit around Earth back in 1991, and spent 14 years studying Earth's ozone layer and our atmosphere in general. In 2005, the satellite was decommissioned because only half of the instruments on board were still functional, and the satellite had already lasted 11 years longer than it's original planned science mission. UARS had some fuel on board which it used as thrust to place itself on a decaying orbit, causing it to eventually fall back to Earth. The satellite will crash land on Earth this Friday afternoon, September 23rd, 2011. As UARS flies through the atmosphere, it is expected to burn up into as many as 26 different pieces ranging from a few pounds up to 400 lbs. These pieces will crash to Earth at speeds of up to 240mph, and are expected to be scattered over a 500mile wide area. NASA does not yet know exactly where the satellite will crash land, but they think it will land somewhere East of North America. If the satellite were to land in a populated area anywhere in the world, the estimated death rate is 1/3200. Hopefully UARS will land harmlessly in the middle of the ocean! Check out Spaceweather.com for more information on where UARS will land, and when you will be able to see it cross the sky. This fireball of a satellite should be visible on Friday even in broad daylight!

What is Space Like?

Ed White, the first American to perform a space walk. Image credit: NASA

You've learned so much about planets, moons, stars, galaxies, and all sorts of other astronomical objects, but do you have any idea about what space is really like? Outer space in general is very very cold. It's temperature is roughly 2.7 Kelvin, or -455 degrees F. Space is almost a perfect vacuum. A perfect vacuum is defined as an area of space with zero gas molecules. Outer space contains about 5 Hydrogen atoms per cubic meter. For comparison, on Earth there is about 10^25 gas molecules per cubic meter (that's a 1 with 25 zeros after it!). Space may be empty of molecules, but it's filled with light, most of which our eyes can't perceive. In the solar system, the sun emits all different types of light, from X-rays to microwaves. Earth's atmosphere blocks a majority of this light, but in outerspace there is nothing to block this light.  These are some of the many reasons why astronauts must wear space suits. With essentially no air to breathe, freezing temperatures, and deadly radiation, an astronaut would survive about 30 seconds if they took off their space suit. NASA has spent many years building spacecrafts and spacesuits that can withstand the harsh conditions in Space. They have done a pretty good job so far, but space is also very unpredictable. You never know what's going to happen out there!

The First Tatooine!

Anyone who has seen Star Wars remembers Tatooine, the home of Luke and Anakin Skywalker. Astronomers have found a real Tatooine! Well, they have found a planet with two suns at least. It's probably nothing like how George Lucas portrayed it though. 

Kepler 16-b is the first circumbinary planet ever discovered. It was first observed by the Kepler Space telescope on July 7th, 2011. The planet orbits a binary star system (Kepler-16) where one star is 70% the mass of the sun and the other is about 25%. In the system, the two stars orbit around each other, and the planet has an orbit surrounding the both of them . The planet is believed to be half rock and half gas,  roughly the size of Saturn, and orbits the stars in about 228 days. An interesting point of the discovery is that the three objects all orbit in the same plane. It's as if the stars and planets are balls on a table, orbiting each other but sitting on an imaginary flat surface. This supports the theory that this planet formed from a circumbinary disk; a disk of gas and dust that surrounded the binary star system as they were forming. Until now, astronomers weren't sure that the conditions were stable enough around a binary star system for a planet to form. The discovery of Kepler 16-b will help astronomers improve their star formation models, and maybe we will find more circumbinary planets in the future!

Image Credit: NASA