Monday, May 17, 2010

Eye Candy

Jupiter

Jupiter is the fifth planet from the Sun and the largest in the Solar System, 1400 times the volume of the Earth, big enough to contain all the other planets and more.

Early models of the Universe placed the Earth at the center, with the Sun and planets revolving around it. In 1609, Galileo started looking at the night sky through a telescope. When he observed the planet Jupiter, he found it was surrounded by several small moons that orbited around it. This suggested that not everything revolved around the Earth. In this way, Jupiter redefined how we consider our place in the Universe.

It takes Jupiter 11.9 Earth years to complete one revolution around the Sun. A day, however, is only 9.9 hours long. This rapid rotation causes an equatorial bulge that is visible when you view the planet through a telescope.

The banded appearance reflects the presence of strong atmospheric currents which have different rotation periods at different latitudes. These bands get their lovely pastel colors from clouds, including the famous Great Red Spot. These colors come from lightning discharges and heat, and some of the chemical compounds may be related to organic molecules that formed on ancient Earth as a prelude to the origin of life.

The darker brown strips across Jupiter are called belts, the brighter strips are zones. Belts are darker because they are cooler, settling lower into the atmosphere.

The belts themselves are more than 200,000 miles wide each. After Jupiter emerged from behind the Sun in 2010, it was mysteriously missing the South Equatorial Belt. Astronomers are uncertain what causes this phenomenon, but it has happened before: in 1973 and again in the early 1990s. In both cases, the planet kept its appearance for a few weeks until the belt eventually returned.

This planet has no solid surface: it is entirely liquid and gas. The surface that we see comes from the uppermost layer of its ever-changing atmosphere, composed of thick clouds of hydrogen and helium.

Although the clouds are all anyone ever sees of Jupiter, they constitute less than 1 percent of the planet's total radius. Underneath the clouds the atmosphere grows denser and hotter under the pressure. Here methane, ammonia, and other trapped gasses may be crushed into tiny rocks, until they eventually cease to behave as gasses. Five thousand miles down, the atmospheric pressure is a million times what it is on Earth. Here liquid hydrogen is compressed into a shiny, metallic substance.

Scientists have fabricated only tiny quantities of metallic hydrogen here on Earth, which has helped explain certain aspects of Jupiter's nature. Its magnetic field is twenty thousand times as strong as Earth's, and extends all the way to Saturn. The presence of highly unstable metallic hydrogen in the core may also be a factor in causing all the electrical storms which are constant in the planet's atmosphere.

There are lots of great books about outer space. My favorite is Astronomy: A Visual Guide, by Mark A. Garlick. It's filled with interesting information and lots of beautiful photographs.

For my previous posts on outer space, click here. For a look at Jupiter's first four known moons, click here.

Always worth checking out is the Hubble Space Telescope, which celebrated its twentieth anniversary last month.

Sunday, May 16, 2010

Eye Candy

The Elements

I've been writing a continuing series of posts on the Periodic Table of Elements, the atoms of which the entire Universe is composed. The last few have been on the lanthanides, or rare-earth elements, found in the first row at the bottom of the periodic table.

The name "rare-earths" is a bit of a misnomer, because several aren't rare at all... they're just not commonly understood, and are found in nature at very low concentrations. Additionally, they are often difficult to extract from the ores in which they are found.

One of the most frequent uses of lanthanide metals is in color television sets, because they glow in distinctive colors when bombarded with electrons.

Europium:
Atomic Symbol: Eu
Atomic Number: 63
Europium is used to coat television picture tubes to give a bright red color. Every time you see the color red on television, it's thanks to the presence of europium. In fact, it was this property which caused early pioneers of television to consider the possibility of developing color.
Europium was found in much higher concentrations than expected in rocks brought back from the surface of the Moon. This unusually high abundance suggests that the Earth and Moon were not formed from the same cosmic material. As yet, there is no generally accepted theory about how the Moon was formed.

Gadolinium:
Atomic Symbol: Gd
Atomic Number: 64
Like several other rare-earth elements, gadolinium is used in television screens. However, it does not produce a vibrant color when exposed to electrons. It is therefore used to control the picture's brightness and contrast, because it gives off bright light without "quenching" the colors of the other elements.
Gadolinium is unique in two respects: first, it has the greatest neutron-capturing ability of any known element, which is put to use in medical techniques like neutron radiography. Second, it is magnetic, like iron, but loses its magnetism when its temperature rises above 20oC. For this reason it is used in video recording and data storage discs which can be permanent or erasable.

Terbium:
Atomic Symbol: Tb
Atomic Number: 65
This is one of the rarest of the rare-earth elements, being four times more expensive than platinum. It has few commercial uses because it is so costly. There was once a plan to use ceramic containing terbium for false teeth because it resembles the gleam of real teeth, but nothing came of it.
Using terbium has led to greater safety when taking X-rays, because it reduces the time the patient is exposed to this dangerous radiation. Terbium allows the same quality image to be produced in a quarter of the time previously required.

A favorite book of mine which has been invaluable in writing these chemistry posts is Nature's Building Blocks: An A-Z Guide to the Elements, by John Emsley. A great recent addition is The Elements: A Visual Exploration, by Theodore Gray, which includes a lot of nice pictures and is suitable for a coffee table near you.

For my previous posts on the elements, click here.

Saturday, May 15, 2010

Eye Candy

Oil!

Petroleum, or crude oil, is a naturally occurring oily liquid found in large quantities below the surface of the earth. It is used as fuel and as raw material in the chemical and plastic industries.

Modern industrial societies use it primarily to achieve a degree of mobility that was unimaginable a hundred years ago. In fact, modern civilization depends on petroleum and its products: the way of life in the suburban communities surrounding great cities are the result of an ample and inexpensive supply of petroleum. Additionally, developing countries exploit petroleum deposits to supply food for their growing populations. All of this is based on the assumption of petroleum availability.

In recent years, worldwide availability of petroleum has steadily declined and its relative cost has increased. Pollution caused by the burning of fossil fuels has created additional complications, causing industrialized nations to consider alternative, non-polluting, renewable fuels. Petroleum will probably cease to be a common commercial material by the mid 21st century.

World production of petroleum was 85 million barrels per day in 2009. The United States, Russia, and Saudi Arabia are the world's largest producers, accounting for about one third of the world's petroleum production. The US is by far the biggest consumer, using 20.6 million barrels per day, more than one fourth of the world's total and double the amount it produces. This forces America to import 13 million barrels of petroleum each day. No other country consumes even half as much.

Petroleum is formed under the earth's surface by decomposed marine life, enmeshed with fine sands that settle to the bottom of sea basins. Such deposits, which are rich in organic material, grow thicker under pressure and from the heat of the Earth's core. The mud and sand harden into shale, and the remains of the dead organisms are transformed into crude oil and natural gas. This process takes millions of years.

Crude oil has been used by humans for thousands of years. In areas where oil bubbled up to the surface, it was used for caulking boats, waterproofing cloth, and fueling torches. During the Renaissance, oil was distilled for lubricants and medicinal products, but the wholesale exploitation of petroleum began in the 19th century. The Industrial Revolution brought a search for new fuels. Various scientists developed processes to make commercial use of petroleum. The Canadian physician Abraham Gessner patented an affordable, oil-based lamp fuel called kerosene in 1852. In 1855, an American chemist named Benjamin Silliman published a paper on the wide range of useful products that could be derived from the distillation of petroleum.

In this way, the quest for greater supplies of crude oil began. The concept of drilling for oil soon followed. With the invention of the automobile and the energy needs brought on by World War I, the petroleum industry became one of the hallmarks of industrial society.

Ocean pollution disturbs marine ecosystems, and is primarily noticed when an oil well at sea is damaged or when an oil carrying ship leaks into the sea as the result of an accident. The 1989 Exxon Valdez and the 2010 Deepwater Horizon disasters are two examples. Despite this perception, most ocean oil pollution is caused by municipal and industrial runoff, cleaning of ships' tanks, and other routine events. Tar, plastic, and sewage wash up on beaches, making swimming hazardous. Plastic, which does not break down in the ocean, is a hazard to sea life. International treaties prohibit disposal of such wastes that can cause these environmental threats, but these treaties are very difficult to enforce.

Scientists agree that burning fossil fuels is a major factor in causing global climate change. The US has attempted to pass laws limiting carbon emissions, such as the "Cap and Trade" bill. So far, these efforts have stalled.

For an insightful look into the history of oil production, check out Oil, by Upton Sinclair.

Saturday, May 8, 2010

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Jellyfish

There are over 3,000 species of jellyfish. Some weigh over 400 pounds, while others are barely visible. They have lived on Earth for over 650 million years, but have no brains, hearts, or skeletal systems. Its tentacles can stretch up to 120 feet. The lion's mane jellyfish may be the longest living animal in the world.

The name jellyfish is actually a misnomer: these animals aren't fish at all. They are part of a group of animals called coelenterates, which also includes corals and sea anemones.
There are two stages in the jellyfish life cycle. First is the polyp stage, when the animal looks like a small stalk on the ocean floor. In the second stage, the animal assumes the familiar umbrella shape, called a medusa, which swims away from the stalk to grow by feeding on plankton. Larger jellyfish may feed on shrimp or small fishes. Prey is captured in the tentacles, where it is stunned or killed by stinging cells called nematocysts. Even a dead or dying jellyfish can sting when touched.

Their behavior is simple: most swim slowly or are carried by ocean currents. Jellyfish appear transparent because less than 5% of their body mass is organic matter, the rest is water.

In recent years, scientists have noticed a huge rise in jellyfish populations in tropical areas, and suspect this increase may be caused by global climate change. So many jellyfish threaten the fishing industry, by preying on fish normally collected by humans. It also creates an obvious nuisance to tourism: jellyfish stings are very painful, and some can be deadly. The venom of some species is as toxic as a cobra's, and can cause death in under three minutes.

Although they have little nutritional value, some varieties are collected as food. Mostly this takes place in southeast Asia, where they are cured with salt to produce a crunchy, crispy texture. In China they are often served raw, with oil dressing or as a salad with vegetables . The cannonball jellyfish is a favorite delicacy, because of its meaty body and because its toxins are harmless to humans.

Biologists are especially interested in a species called turritopsis nutricula, because it appears to be immortal. This jelly, found in the Caribbean Sea, can change from a medusa back to the polyp stage, allowing it to enter another life cycle, and another after that. Some individual turritopsis might be thousands of years old. Researchers think humans may one day be able to live up to 500 years if this process can be duplicated.

Most famous of all is the giant, dangerous, Portuguese Man-Of-War. It is common in tropical seas, floating on the surface with a brightly colored, gelatinous mass. This is actually a colony of hundreds or thousands of individual animals, living together for mutual defense. They have no independent means of propulsion, and travel either by floating in the currents or by catching wind with their billowing sails. When threatened, they can deflate the airbag and briefly submerge. The tentacles typically grow to over 60 feet in length, and have sunk ships by getting tangled underneath them.

Finally, it is a myth that urine cures a jellyfish sting. So don't try it.

There's a cool, two minute video worth checking out below:


This is my second blog post on animal life. For the first one, on sponges, click here.

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Friday, May 7, 2010

Space Shuttle

NASA has announced the final voyage of the space shuttle Atlantis will launch next week, on May 14 at 2:20 PM. Commander Ken Ham will lead the expedition. Atlantis will be flying to the International Space station (ISS), carrying a crew of six and a load of supplies. NASA is retiring its remaining shuttles by the end of 2010.

The American space shuttle is still the world's only fully reusable space vehicle. Originally there were six members of the fleet: Enterprise, Columbia, Challenger, Discovery, Atlantis, and Endeavor. Enterprise was only built for test missions and was never flown into space. Columbia flew the first real missions, beginning in 1981. After the losses of Challenger in 1986 and Columbia in 2003, only three active shuttles remain in use. After the final voyage of Atlantis, there will be only two.

After the first Apollo missions to the moon, President Richard Nixon wanted to continue exploration, but wanted to reduce the costs of space travel. He reasoned that if the US had reusable space vehicles instead of the "one time use only" vessels like Apollo, it could afford to explore a lot more.

Today there are two main manned space vehicles: the American space shuttle and the three-stage Russian Soyuz rocket. The space shuttle missions have carried out a variety of experiments, transported satellites into orbit, and performed repairs and upgrades on the Hubble Telescope. Their most ambitious enterprise began in 1999: the construction of the ISS in cooperation with Japan, Russia, and the European Space Agency. Its symbolism of peace and cooperation between former enemies, America and the Soviet Union, cannot be overstated.

The shuttle program suffered a tragic setback on 28 January, 1986, when Challenger exploded minutes after launching, killing its entire crew, including a high school teacher, the first ordinary citizen to fly into space. Shuttle flights were suspended until 1988. Tragedy struck again in 2003 when Columbia was destroyed. This accident raised concerns for astronaut safety, and delayed construction of the ISS for several years.

President Barack Obama has not called for the construction of a new space fleet, but has a strategy for the exploration of space that will send man to an asteroid by 2025 and Mars by 2035.

With the space shuttle program entering its last year, many argue that manned space missions waste resources. Why send people into space when you can send probes for a fraction of the cost and with none of the risk to astronauts' lives? It might be wiser to use probes and deep space telescopes like Hubble to search space for someplace worthwhile to go before sending humans on dangerous and arbitrary missions. Plans to build a new manned space fleet and send humans to Mars remain in the embryonic stages.

There are lots of great books about outer space. My favorite is Astronomy: A Visual Guide, by Mark A. Garlick. It's filled with interesting information and lots of beautiful photographs.

For my previous posts on outer space, click here.