Universe Today

March 9, 2009April 26, 2016 by Fraser Cain

Core of the Earth

The Earths interior (University of Chicago)

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Scientists believe that deep down inside the Earth, there’s a huge ball of liquid and solid iron. This is the Earth’s core, and it protects us from the dangerous radiation of space.

When the Earth first formed, 4.6 billion years ago, it was a hot ball of molten rock and metal. And since it was mostly liquid, heavier elements like iron and nickel were able to sink down into the planet and accumulate at the core. The core is believed to have two parts: a solid inner core, with a radius of 1,220 km, and then a liquid outer core that extends to a radius of 3,400 km. The core is through to be 80% iron, as well as nickel and other dense elements like gold, platinum and uranium.

The inner core is solid, but the outer core is a hot liquid. Scientists think that movements of metal, like currents in the oceans, create the magnetic field that surrounds the Earth. This magnetic field extends out from the Earth for thousands of kilometers, and redirects the solar wind blowing from the Sun. Without this magnetic field, the solar wind would blow away the lightest parts of our atmosphere, and make our environment more like cold, dead Mars.

Although the Earth’s crust is cool, the inside of the Earth is hot. The mantle is only about 30 km beneath our feet, and it’s hot enough to melt rock. At the core of the Earth, temperatures are thought to rise to 3,000 to 5,000 Kelvin.

Since the core is thousands of kilometers beneath our feet, how can scientists know anything about it? One way is to just calculate. The average density of the Earth is 5.5 grams per cubic cm. The Earth’s surface is made of less dense materials, so the inside must have something much more dense than rock. The second part is through seismology. When earthquakes rock the surface of the Earth, the planet rings like a bell, and the shockwaves pass through the center of the Earth. Monitoring stations around the planet detect how the waves bounce, and scientists are able to use this to probe the interior of the Earth.

We have written many articles about the Earth for Universe Today. Here’s an article about how the Earth might actually have an inner, inner core.

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.

Sources:
http://en.wikipedia.org/wiki/Structure_of_the_Earth
http://scign.jpl.nasa.gov/learn/plate1.htm

March 9, 2009December 24, 2015 by Tammy Plotner

The Basketball Player In The Moon – Catch It Tonight!

The Basketball Player In The Moon - Ed Murray

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You’ve heard about the Man In the Moon and the Lady in the Moon… If you’re into lunar observing then you know about the Cow Jumping Over the Moon and the Rabbit in the Moon, too. But have you ever heard about the Basketball Player In The Moon? Well, step inside and find out more…

First discovered by Ed Murray and published in ALPO’s monthly “The Lunar Observer” and in NASA’s Dr Tony Phillips November 13, 2008 issue of Spaceweather.com, the “basketball player” is a compilation of lunar features that resemble… well… a basketball player! How did it’s discovery come about? Just ask Ed.

“Like many amateur astronomers, I guess I’ve always daydreamed just a little bit about possibly discovering a faint fuzzy that turns out to be a bright comet, but very quickly, I have to come down to Earth because living in suburban Philadelphia, with our weather and horrid light pollution, the chance of that happening are slim to none. So, I’ve had to be content with the memories of being able to see the solar eclipse from Hawaii, where I happened to see the Milky Way in all it’s glory from the 9,000 ft level visitors center, the annular eclipse of 1994 in New York… seeing the shadow bands … not on a white sheet but freshly cut green grass, numerous Aurorae and everything else…. until one night….”

Yes! Yes. That one grand night when one plus one makes two. And two suddenly makes sense! “Like many, I did have that National Geographic Map of The Moon but after numerous moves across the country and two college dorms, it, like many things, lay in tatters and eventually found it’s way to the great map room in the sky. So, you might understand how happy I was to find out that National Geographic had re-issued it and I could purchase another copy and so it remained opposite my bed for a few years… Until one night last year… When I looked at it and saw the basketball player, and promptly forgot it. Saw it a second time and forgot it. Saw it a third time, early on May 12. 2008 and realized that maybe this is something I should check out.”

And check it out he did. As a Dark Sky Advocate and once President of the Bucks-Mont. Astronomical Association, Ed double checked what he could see from his maps with what he could see against the sky and came to the same conclusion. It looks like a basketball player. Like all good observers, he turned in his findings to as many organizations and observing clubs as he could. Of course, Fritz Zwicky would have sure understood the response he got from the “professionals”, but the rest of the world will be happy to know that the Basketball Player has been added to the roles of the Unofficial Lunar Nomenclature site and acclaimed by SpaceWeather.

When can you see the Basketball Player In The Moon? When it rises tonight would be a great time to start. This is when the lunar east limb will appear to make the “player” be upright and easiest to spot. Later in the evening, as the Moon progresses across the sky, the view will appear to turn sideways. Still there… Just oriented a little differently! If you’re clouded out tonight, try again tomorrow – or whenever the Moon nears Full.

In the meantime? Why not wish Ed a big round of congratulations for an observing job – and discovery – well done!

March 9, 2009December 24, 2015 by Nancy Atkinson

March Madness for Space Geeks

Have you ever looked on with envy at your office mates’ brackets and (illegal) betting pools for the NCAA basketball tournament but you don’t know the difference between a jump ball and a jump shot? Well, now there’s a bracket just for you: March Mission Madness. And it’s a showdown of epic proportions, plus it’s not even against the law to participate (as long as no money is changing hands!) With NASA’s March Mission Madness, you can enjoy intriguing matchups, story lines and buzzer beating drama. Beginning today, March 9th, NASA fans will be able to view the lineup of 64 NASA missions, learn about mission goals, and vote for your favorite missions, as well as predict which missions your fellow space geeks and nerds will vote for during this single elimination tournament. There will even by play-by-by commentary from Miles O’Brien and Keith Cowing. Sound like fun? Here’s how to participate:

How to Play

There are two ways to participate in the 2009 Mission Madness Tournament. First, visit the website, http://www.nasa.gov/missionmadness, from March 9th – 18th to learn which missions are competing head to head, print your bracket and make your predictions. You can print out as many brackets as you like to evaluate endless winning scenarios.

Second, return to the website and vote for your favorite missions during each round, starting on March 19. You are allowed to vote for your favorite missions as many times as you like, so be sure to support your favorite missions to help them advance deep into the tournament. As voting is completed for each round, the winning missions advance allowing you to see how your predictions compare to all of the voters.
Round one features 32 predetermined matchups. Each round consists of two days of online voting with the winning missions advancing in head to head competition. Fans will be able to vote for their favorite missions as many times as they like while polls are open, with the very first Mission Madness Championship Winner determined on April 8th, 2009.

Here’s the tournament schedule:

March 9th – 18th Brackets available on the web site with the head to head line-ups for each region.

March 19th – 20th Round 1 Voting

March 23rd – 24th Round 2 Voting

March 26th – 27th Sweet Sixteen Voting

March 30th – 31st Quarter Final Round Voting

April 2nd – 3rd Semi Final Round Voting

April 6th – 7th Final Round Voting

April 8th NASA EDGE names 2009 Mission Madness Winning Mission

Source: NASA

March 9, 2009December 24, 2015 by Nancy Atkinson

Fermilab Scientists Discover Rare Single Top Quark

This proton-antiproton collision, recorded by the DZero collaboration, is among the single top quark candidate events. The top quark decayed and produced a bottom quark jet (b jet), a muon and a neutrino. Credit: DZero collaboration.

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Scientists at Fermilab have observed particle collisions that produce single top quarks, a 1 in 20 billion find. This discovery confirms important parameters of particle physics, including the total number of quarks. Previously, top quarks had only been observed when produced by the strong nuclear force. That interaction leads to the production of pairs of top quarks. The production of single top quarks involves the weak nuclear force and is harder to identify experimentally. This observation occurred almost 14 years to the day of the top quark discovery in 1995.

Fermilab’s Tevatron, located near Chicago, Illinois is currently the world’s most powerful operating particle accelerator, and the discovery was made by scientists working on together on collaborations. Scientists say finding single top quarks has significance for the ongoing search for the Higgs particle.

The Fermilab accelerator complex. Credit: Fermilab

“Observation of the single top quark production is an important milestone for the Tevatron program,” said Dr. Dennis Kovar, Associate Director of the Office of Science for High Energy Physics at the U.S. Department of Energy. “Furthermore, the highly sensitive and successful analysis is an important step in the search for the Higgs.”

Searching for single-top production makes finding a needle in a haystack look easy. Only one in every 20 billion proton-antiproton collisions produces a single top quark. Even worse, the signal of these rare occurrences is easily mimicked by other “background” processes that occur at much higher rates.
Discovering the single top quark production presents challenges similar to the Higgs boson search in the need to extract an extremely small signal from a very large background. Advanced analysis techniques pioneered for the single top discovery are now in use for the Higgs boson search. In addition, the single top and the Higgs signals have backgrounds in common, and the single top is itself a background for the Higgs particle.

To make the single-top discovery, physicists of the CDF and DZero collaborations spent years combing independently through the results of proton-antiproton collisions recorded by their experiments, respectively.

CDF is an international experiment of 635 physicists from 63 institutions in 15 countries. DZero is an international experiment conducted by 600 physicists from 90 institutions in 18 countries.

The CDF detector, about the size of a 3-story house, weighs about 6,000 tons. Credit: Fermilab

Each team identified several thousand collision events that looked the way experimenters expect single top events to appear. Sophisticated statistical analysis and detailed background modeling showed that a few hundred collision events produced the real thing. On March 4, the two teams submitted their independent results to Physical Review Letters.

The two collaborations earlier had reported preliminary results on the search for the single top. Since then, experimenters have more than doubled the amount of data analyzed and sharpened selection and analysis techniques, making the discovery possible. For each experiment, the probability that background events have faked the signal is now only one in nearly four million, allowing both collaborations to claim a bona fide discovery that paves the way to more discoveries.

“I am thrilled that CDF and DZero achieved this goal,” said Fermilab Director Pier Oddone. “The two collaborations have been searching for this rare process for the last fifteen years, starting before the discovery of the top quark in 1995. Investigating these subatomic processes in more detail may open a window onto physics phenomena beyond the Standard Model.”

Source: Fermilab

March 9, 2009December 24, 2015 by Fraser Cain

Earth’s Early Atmosphere

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The atmosphere we enjoy today is radically different from the atmosphere that formed with the Earth billions of years ago. And yet, the Earth’s early atmosphere somehow transformed into the life giving atmosphere we enjoy today.

The Earth formed with the Sun 4.6 billion years ago. At this point, it was nothing more than a molten ball of rock surrounded by an atmosphere of hydrogen and helium. Because the Earth didn’t have a magnetic field to protect it yet, the intense solar wind from the young Sun blew this early atmosphere away.

As the Earth cooled enough to form a solid crust (4.4 billion years ago), it was covered with active volcanos. These volcanos spewed out gasses, like water vapor, carbon dioxide and ammonia. This early toxic atmosphere was nothing like the atmosphere we have today.

Light from the Sun broke down the ammonia molecules released by volcanos, releasing nitrogen into the atmosphere. Over billions of years, the quantity of nitrogen built up to the levels we see today.

Although life formed just a few hundred million years later, it wasn’t until the evolution of bacteria 3.3 billion years ago that really changed the early Earth atmosphere into the one we know today. During the period 2.7 to 2.2 billion years ago, these early bacteria – known as cyanobacteria – used energy from the Sun for photosynthesis, and release oxygen as a byproduct. They also sequestered carbon dioxide in organic molecules.

In just a few hundred million years, this bacteria completely changed the Earth’s atmosphere composition, bringing us to our current mixture of 21% oxygen and 78% nitrogen.

We have written many articles about the Earth for Universe Today. Here’s an article about how the Earth’s early atmosphere was very different from the one we see today, and an another that describes how Titan’s atmosphere is probably similar to the Earth’s early atmosphere.

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.

March 9, 2009December 24, 2015 by Fraser Cain

Composition of the Earth’s Atmosphere

Breathe in and you can appreciate that the Earth’s atmosphere has everything needed to support life on Earth. But what’s in it? Let’s take a look at the composition of the Earth’s atmosphere. Of course, things haven’t always been balanced they way they are today. But more of that in a second.

The Earth’s atmosphere is composed of the following molecules: nitrogen (78%), oxygen (21%), argon (1%), and then trace amounts of carbon dioxide, neon, helium, methane, krypton, hydrogen, nitrous oxide, xenon, ozone, iodine, carbon monoxide, and ammonia. Lower altitudes also have quantities of water vapor.

The atmosphere we have today is very different from the Earth’s early atmosphere. When the planet first cooled down 4.4 billion years ago, volcanos spewed out steam, carbon dioxide and ammonia, and it was 100 times as dense as today’s atmosphere.

The earliest bacteria, known as cyanobacteria, were probably the first oxygen-producing organisms on Earth. Approximately 2.7 to 2.2 billion years ago, they released large amounts of oxygen and sequestered the carbon dioxide. As oxygen was released, it reacted with ammonia to release nitrogen. The carbon dioxide in the atmosphere is exhaled by plants (and produced by human industry burning fossil fuels).

We have written many articles about the Earth for Universe Today. Here’s an article about how the Earth’s atmosphere is slowly leaking into space, and here’s an article about how the early Earth’s atmosphere was similar to Titan’s atmosphere.

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.

March 8, 2009December 24, 2015 by Jerry Coffey

Size of the Earth

Mars Compared to Earth. Image credit: NASA/JPL

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The size of Earth, like the size of all of the celestial bodies, is measured in a number of parameters including mass, volume, density, surface area, and equatorial/polar/mean diameter. While we live on this planet, very few people can quote you the figures for these parameters. Below is a table with many of the pieces of the data used to measure the size of the Earth.

Mass	5.9736×10²⁴kg
Volume	1.083×10¹² km³
Mean diameter	12,742 km
Surface area	510,072,000 km²
Density	5.515 g/cm³
Circumference	40,041 km

Those numbers tell you the size of the Earth, but what about its other statistics? The atmospheric pressure at the surface is 101.325 kPa, average temperature is 14°C, the axial tilt is approximately 23°, and it has an orbital speed of 29.78 km/s. Earth orbits with a perihelion of 147,098,290 km, and an aphelion of 152,098,232 km, making for a semi-major axis of 149,598,261 km. Even though we need oxygen to survive, it is the second most abundant component of Earth’s atmosphere. Nitrogen accounts for 78% of the gases in the atmosphere and oxygen occupies 21%.

The Earth only has one moon. That is pretty uncommon in our Solar System. There are currently 166 recognized moon in our system. There is one asteroid that has a quasi relationship with Earth. 3753 Cruithne has a 1:1 orbital resonance with the Earth. It is a periodic inclusion planetoid that has a horseshoe orbit. It was discovered in 1986.

Since we occupy this planet, it is understandably the most extensively studied body in space. We have sent scientist to most of the corners of our world. Yet, we find dozens of new species each year and there are areas that have rarely seen a human’s footprints. There are aspects of our world that we do not understand and have theories too inadequate to explain. Science is light years ahead of where it was just 50 years ago. These advancements are exciting enough to make the possibilities of the near future seem boundless.

Now that you know the size of the Earth, you could look for information on extremophiles, the Mariana Trench, and the Tunguska event. Earth bound events are often taken for granted since we live here, but, with a little research, you may find much more excitement outside of your back door than you ever expected.

We have written many articles about the Solar System for Universe Today. Here’s an article about the size of Mars, and here’s one about the size of the Moon.

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.

Sources:
NASA Earth Facts
NASA Solar System Guide on Earth
NASA Solar System Orbit Diagram

March 7, 2009December 29, 2015 by Nancy Atkinson

Carnival of Space #93

It’s a Carnival of exoplanetary proportions! This week’s Carnival of Space is hosted by Emily Lakdawalla at The Planetary Society. With the launch of Kepler there’s lots of interesting posts about exoplanets, and lots of other great links, too. Check it out!

And if you’re interested in looking back, here’s an archive to all the past carnivals of space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, let Fraser know if you can be a host, and he’ll schedule you into the calendar.

Finally, if you run a space-related blog, please post a link to the Carnival of Space. Help us get the word out.

March 6, 2009December 24, 2015 by Anne Minard

Success: Kepler Lifts Off to Look for Other Earths

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316404main_ksc_030609_kep_grab_1 — Kepler as it appeared moments prior to launch in Florida. Credit: NASA

NASA’s Kepler mission lifted off without a hitch just before 11 p.m. local time Friday from Cape Canaveral Air Force Station in Florida.

The launch was a bit of a nail-biter, coming on the heels of last week’s failure of the Orbiting Carbon Observatory, which plummeted into the ocean when its fairing malfunctioned. But everything for the Kepler launch — from the weather to the countdown — went flawlessly. At five minutes to launch, Kepler’s rockets sent ribbons of smoke into Florida’s 65-degree Fahrenheit (18-degree Celsius) nighttime air under perfectly clear skies. With 30 seconds left, confirmation commands were exchanged with practiced precision. The casing (called the fairing) fell off with grace, and three minutes into the flight, the craft was cruising away from Earth at nearly 7,000 miles (11,265 kilometers) per hour. Each launch event happened within three seconds of its predicted time.

Kepler’s engines shut down at 11:45 p.m. U.S. eastern time, and the craft achieved separation just before midnight, about 62 minutes after launch. Now, for the next three and a half years, Kepler will trail Earth in orbit and stare at a single patch of sky in the Cygnus-Lyra region of the Milky Way.

Kepler fires the imagination, as it could finally address the age-old question of whether we Earthlings are alone. William Borucki, NASA’s principal investigator for Kepler science, spoke about the mission at a recent NASA press conference and said if Kepler spies Earth-like planets in the habitable zones of other stars, “life may well be common throughout our universe. If on the other hand we don’t find any, that will be another profound discovery. In fact it will mean there will be no Star Trek.”

The $500 million Kepler mission will spend three and a half years surveying more than 100,000 sun-like stars in Cygnus-Lyra. Its telescope is specially designed to detect the periodic dimming of stars that planets cause as they pass by.

By staring at one large patch of sky for the duration of its lifetime, Kepler will be able to watch planets periodically transit their stars over multiple cycles, allowing astronomers to confirm the presence of planets and use the Hubble and Spitzer space telescopes, along with ground-based telescopes, to characterize their atmospheres and orbits. Earth-size planets in habitable zones would theoretically take about a year to complete one orbit, so Kepler will monitor those stars for at least three years to confirm the planets’ presence.

Astronomers estimate that if even one percent of stars host Earth-like planets, there would be a million Earths in the Milky Way alone. If that’s true, hundreds of Earths should exist in Kepler’s target population of 100,000 stars.

March 6, 2009December 24, 2015 by Anne Minard

Finally, It’s Go Time for Discovery Launch

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After four delays in a month’s time, NASA’s Discovery shuttle will finally depart the Kennedy Space Center at 9:20 p.m. local time on Wednesday, March 11.

Discovery’s STS-119 mission will carry two new solar array wings, which will increase the station’s solar power capacity so it might support a larger crew. Launch was initially set for early February, but managers were worried following a malfunction of hydrogen control valves on the shuttle Endeavour last fall. They wanted to rule out any similar glitches on Discovery.

Discovery’s launch date was announced following a flight readiness review earlier today. During the meeting, top NASA and contractor managers assessed the risks associated with the mission and determined the shuttle’s equipment, support systems and procedures are ready.

On the resolution of the shuttle’s flow control valve issue, John Shannon, Space Shuttle Program manager said, “This is one of those problems requiring a lot of work. It was a little premature before today. The signs were there that we were safe, but the teams went off and came up with definitive data to prove it.”

Mike Leinbach, Space Shuttle launch director, added that from a processing standpoint, the shuttle is in good shape. “It feels good to be here with a firm launch date. I saw a lot of people after the meeting and the mood is really upbeat,” he said.

The launch countdown clock will begin at the T-43 hour mark at 7 p.m. on Sunday. Also on Sunday, Discovery’s astronauts are scheduled fly from their home base in Houston, arriving in arriving in Florida by mid-afternoon.

Source: NASA