By Brady Anderson
Growing up as a boy in a small farming community in rural Nebraska one of my favorite things to do was to stare at the night sky. It was always so beautiful. I would often fantasize of traveling from planet to planet to uphold intergalactic peace as a Jedi knight. Among these imaginations I always wondered where all these planets came from. I especially always wondered where the moon came from. Was it really made of cheese? Did a man truly live there? Could a cow jump over it? And was there actually anything worth seeing on its dark side? Well, now that I am older I don’t look at the sky as often as I used too—darn city lights!—but I do still wonder how exactly the moon come about. As it turns out many in the scientific community have also been concerned with this question and over the years there have been a few different theories as to the origin of the moon.
If found some theories about how the moon was formed on the Planetary Science Institute’s website. One theory is that the moon was a planet that was form around the same time as the earth was formed but was pulled into orbit around the earth due to its smaller density. This theory was largely discredited because the moon does not have any iron. The lack of iron is evidence that the moon was not formed from the same process as the earth was because if it was it would contain iron as the earth does. In response to this lack of iron another theory suggested that the moon formed in some other part of the solar system where there was little iron and was then somehow captured into earth’s orbit. This was disproved when lunar rocks were analyzed and showed the same isotope composition as the earth. The fact that they have the same isotope composition gives evidence that the earth and the moon were formed in the same area of the solar system. Another theory suggested that the moon the early earth was spinning so quickly that the moon flung off the earth. However, it has been proven that the angular momentum and energy need for such a thing to happen are impossible given what we know about the size and composition of the earth and moon.
The leading theory of the moon’s origin is an idea put forward by Dr. William K. Hartman and Dr. Donald R. Davis (http://www.psi.edu/projects/moon/moon.html). They proposed that the moon was formed by a body about the size of mars impacting the earth some around 60 million years after the earth’s initial accretion (Earth System History Third Edition, p. 248). Apparently this celestial body blasted into the earth with such speed and impact that some of the mantle of the body was separated to form what is now the moon. The Planetary Science Institute (http://www.psi.edu/projects/moon/moon.html) shows a computer simulation of what the impact probably looked like.
This impact theory explains several facts about the moon and so lend to its probability. First, the moon does not have any water whatsoever. The theory suggests this is so because water and other compounds were expelled from the moon during its formation. Second, the moon has a small metallic core. This is explained by the theory because when the mars sized body impacted the earth its core sank into the earth and became part of its core, but the body’s mantle exploded from it to form the small core of the moon. Third, the moon has a feldspar-rich outer layer. The theory accounts for this because of the heat involved in the impact formation of the moon. The early moon would have had a magma ocean early on much like the early earth (Earth System History Third Edition, p. 248-249).
So there you have it! The moon was most likely formed from an impact of a smaller celestial body on the earth. It was definitely not made of cheese.
Courtesy Public domain (via Wikipedia)Fifty years ago today, 27 year-old Soviet cosmonaut Yuri Alekseyevich Gagarin became the first human to be launched into space. On April 12, 1961, Gagarin and the Soviet Vostok-1 spaceship were sent skyward for a 108 minute ride above and around Earth. He made a single orbit around the planet before returning to earth where he received a hero's welcome and became an instant celebrity world-wide. The feat accelerated the so-called Space Race between the Soviet Union and the United States. A mere eight years later, US astronauts Neil Armstrong and Buzz Aldrin became the first humans to walk on the Moon on July 20, 1969. Unfortunately, Gagarin didn't live to see that day, having died the year before in a crash while test-flying a Soviet MiG jet.
Courtesy NASA/JPL-Caltech Yesterday NASA's Stardust spacecraft performed a final burn with its main engines which effectively ended the life of NASA's most traveled comet hunter. Called a "burn to depletion", the procedure will help to answer the question of how much fuel Stardust had left in its tank. While it sounds like running your snow blower until it runs out of gas to store it for the summer, this was an important test as no one has invented an entirely reliable fuel gauge for spacecraft. Part of the process of approximating fuel use is looking at the history of the vehicle's flight and how many times and for how long its rocket motors have fired.
Stardust's burn to depletion is expected to be useful especially because the spacecraft has been proverbially "running on empty" for a long time. Stardust has been in space for over 11 years and has flown past an asteroid (Annefrank), collected particle samples from a comet (Wild 2) and returned them to Earth in a sample return capsule in January 2006. Then, after these primary objectives, it was then re-tasked to perform a flyby of comet Tempel 1, a task it completed last month.
Before the burn to depletion Stardust pointed its antenna at Earth and sent information on the burn as it happened. The command ordering the rockets to fire was sent for 45 minutes, but the burn lasted just 146 seconds. 20 minutes after the engines burned out, Stardust's computer commanded its transmitters to turn off. Without fuel to power the spacecraft's attitude control system, Stardust's solar panels will not remain pointed at the sun. When this occurs, the spacecraft's batteries are expected to drain of power and deplete within hours.
Its a fitting end to a very impressive mission for NASA.
Courtesy NASA/ESA/Garth Illingworth (UCSC)/Rychard Bouwens (UCSC/Leiden University)/HUDF09 TeamThe Hubble Space Telescope has captured what astronomers are claiming is the oldest galaxy in the universe. Here's some of what NASA's Hubble website says about the discovery:
The farthest and one of the very earliest galaxies ever seen in the universe appears as a faint red blob in this ultra-deep–field exposure taken with NASA's Hubble Space Telescope. This is the deepest infrared image taken of the universe. Based on the object's color, astronomers believe it is 13.2 billion light-years away.
The dim object is a compact galaxy of blue stars that existed 480 million years after the Big Bang, only four percent of the universe's current age. It is tiny and considered a building block of today's giant galaxies. Over one hundred such mini-galaxies would be needed to make up our Milky Way galaxy.
Think of that - the light from this object we're seeing now took 13.2 billion years to reach our eyes. That's mind-boggling. We're actually looking back in time. Anyway, the study which appears in the journal Nature, was led by Rychard Bouwens at the Leiden Observatory in the Netherlands, and Garth Illingworth, of the University of California, Santa Cruz. The tiny smudge of light will be further studied and confirmed when the infrared-optimized James Webb Space Telescope is up and running in 2014.
By the way, the Hubble Space Telescope is featured in one of five films at this year's Omnifest playing now through February 17th here at the Science Museum of Minnesota. Take it from me, the images in the film are quite spectacular and worth seeing.
According to the Aurora Alert mailing list, a solar event on Dec 14th may produce auroral displays (northern lights) starting around midnight tonight, Wednesday 12/15, and continuing Thursday 12/16 and possibly Friday 12/17. Your best bet for seeing the lights -- if they occur -- is to get away from the city, find a dark place with a clear view to the north, and look low on the horizon. Clouds will block your view, so if it's overcast, don't bother.
Now that's some boomin' bass.
New data from a French satellite launched to detect really low frequency waves--way deeper than the tune bumpin' from that Escalade next to you at the stop light--generated by the earth, saw some significant activity right before the Haitian earth quake, last January. While earthquake prediction is always going to be a difficult nut to crack, these sorts of satellite based measurements could be another useful tool in staying clear of shaky ground.
Courtesy EeekBig news from NASA today, y'all.
NASA scientists are holding a conference at 2:00 EST today, and I hate to spoil the surprise, but word on the street is that they've discovered life on the planet Earth. Ah... but it's not what you think—word is that they've discovered life that's really different from everything else here.
Last year, I posted about the theory that this sort of thing might exist, but it wasn't until now that it has actually been discovered. Here's the gist: bacteria living in the mud of weirdo Mono Lake have been found to use arsenic as a building block of their bodies. That may not sound like much, but, if it's true, it would mean that these bacteria are different than every other living thing on this planet. Everything else that lives on this planet is made of carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. These creatures use arsenic instead of phosphorous.
Aside from being super cool and different, the discovery suggests that if life can exist in ways we didn't think was possible, it can exist in places we didn't think life was possible. Like other planets and moons in our own solar system.
More details after the conference, hopefully.
Courtesy European Space AgencyHere in Minnesota we live the land of political recounts. But in the world of astronomy, a recount on the density of the heavens is leading to the conclusion there might be three times as many stars in the sky than we have thought in the past. Just how many stars are there? You'll have to click this link to get that astronomically large number.
This past week on November 17th, the Leonid Meteor Shower sent meteors streaming down on Earth. "Shooting stars," or meteors, are actually bits of debris in space that burn up upon entering the earth's atmosphere at high speed. Technically, the meteors don't run into the Earth, the Earth runs into the meteors.
The trail of debris in space that the Earth encounters every November 17th was laid down by the comet Tempel-Tuttle. The comet orbits the sun and has made many orbits, laying down a trail of dust and debris on each pass. The comet was first recorded in the year 1366 and has an orbit period of 33 years.
This year was not a spectacular show. The peak, the time when earth passes though the densest part of the trail, only produced about 20 meteors per hour. There have been spectacular years when the Leonids produce meteor storms. These tend to occur every 33 years and there can be thousands of meteors per hour. The next storm probably won't be until around the year 2042.
This year, it was cloudy at my home so I "observed" the shower in a completely different way. I listened to it.
Let me explain.
The US Air Force runs the Space Surveillance Radar in Kickapoo, Texas. There's a lot of junk in space and when the government is flying multimillion dollar craft up there they want to keep them safe. Twenty-four hours a day the space radar puts out 800 kilowatts of continuous wave power at 216.98 Mhz. It sounds like a steady tone on a receiver. The primary mission is to monitor everything in orbit. It can detect objects as small as 10 centimeters orbiting at up to 30,000 km above earth. The radar works by having the signal bounce off objects and reflect the signal back to a number of listening stations.
During a meteor shower, meteors streak through the atmosphere and create a trail of ionized dust. The radio signal reflects off this trail and we can hear the signal of the radar change. Space Weather Radio, a private group, has a listening station set up by Stan Nelson on the roof of his house a couple hundred miles away in Roswell, NM. Space Weather Radio streams the signal over the web and you can listen in. During a meteor shower, you can recognize meteors by the sound.
I recoded for an hour and successfully heard the signature sound of meteors streaking through the atmosphere. For sure a cool experience on an otherwise cloudy night.