Tag: space

Exploring Space: Extrasolar planets

Notice the planet in the lower right corner? (Image from the Hubble Space Telescope via Wikipedia).

One of the neatest developments in recent space exploration has been the accelerating discovery of planets orbiting other stars. Other stars are just so far away that it’s insanely difficult to see anything orbiting them. Also, the stars can be much brighter, a billion times even, than the planets. So, in the beginning, they could just identify the largest of planets, Jupiter sized and bigger, because of they way they make their stars wobble, but this and other techniques have gotten better and better and now we’re looking at smaller and smaller planets, getting down to Earth sized objects.

Methods for detecting planets orbing other stars. Image by M. Perryman.

One of my students, in investigating modern space exploration, found The Extrasolar Planets Encyclopaedia, which is pretty sweet because it keeps a running tally of planets found outside our solar system. When he found it last week the number was 502, now it’s 504. The site also has a long list of the ground and space based projects looking for extrasolar planets, which demonstrates how active the field is today.

Life on Mars

Discover Magazine has a great article summarizing the evidence for life on Mars. It’s long because it goes into a lot of detail examines quite a variety of possibilities, but it ties quite nicely in with the questions we are asking about what is life and where it can be found.

The article also mentions a study titled, “The Limits of Organic Life in Planetary Systems” produced by the National Research Council for NASA. It can be found for free online, with an associated podcast that much more accessible to middle schoolers. The report is extremely open to the possibility that extra-terrestrial life exists, and could exist even without water and might even be silicon based.


Artistic satellite views of the Earth

The Tibetian Plateau. Image from the satellite Landsat 5 via the Eros Image Gallery.

For the geography nerds, but perhaps also for those with an appreciation of the natural beauty of the world. The US Geological Survey has a series of satellite pictures chosen just for their sheer beauty.

The Landsat satellites that take these pictures usually photograph in more than just the human-visible color spectrum. For many geologic and environmental purposes, different infra-red wavelengths are often better for seeing details on the Earth’s surface. The USGS has a nice primer on the Landsat program. Many of the color images posted here were reconstructed from different color bands.

Yukon delta. Image from Landsat 7: Earth as Art 3 collection.

The resulting images can be exceptionally beautiful and somewhat surreal. I like that there is an abstract surface beauty, divorced from the content, meaning and understanding that a closer analysis of the images yields to the eye of the trained observer: delicate swirls of algae might be signs of eutrophication to a biologist; dendritic deltas tell the geologist about sediment load, offshore currents and mass balance.

Phytoplankton bloom around the Swedish island of Gotland in the Baltic Sea is reminiscent of Van Gogh's Starry Night. Image from Landsat 7.

Extraterrestrials: Exploring space for signs of life

Intelligent Life

One of the major motivations space exploration is the search for extra-terrestrial life. The SETI project is the most visible initiative and there are a lot of neat educational resources on their outreach page. And you can participate. seti@home allows you to download a screensaver that actually helps them process data.

Arecibo Observatory in Puerto Rico, which is used (a little) for the SETI project. Image by Jaro Nemcok on Wikipedia.

The NPR program, To the Best of Our Knowledge, has a nice program asking the question, “What is Life?” The last part of the program (at about 45:00 minutes in) is an interview with Paul Davies who is head of the SETI post-detection task group. It starts with question of silicon based life, the theory of which is based on the locations of carbon and silicon in the same column in the periodic table. It also talks about what life might look like once technology really takes off and life starts “evolving by design”.

Finding life as we know it

But SETI searches for signs of intelligent life using radiotelescopes. There are other projects that look for any sign of live. One of the major reasons the Mars rovers and satellites spend a lot of time looking for signs of water on the planet is that life, as we know it, requires water.

Europa: Image from NASA.

It’s also why space agencies are so interest in Europa, the moon of Jupiter that’s covered with ice. Europa also has signs of volcanic activity under the ice, which makes it doubly interesting.

About The Elegant Universe

NOVA’s program The Elegant Universe has an excellent website where the entire three hour video is available for free (with a full screen option). They have also broken the video up into segments and have a great teachers’ page which summarizes what’s in each segment.

The Elegant Universe's Teachers' page is excellent.

Created in 2003, when string theory was making it’s big splash in the popular consciousness, The Elegant Universe starts with Newton’s observations of gravity, shows Einstein’s separate explanations of why gravity works and the nature of the sub-atomic world, and finally delves into string theory which tries to reconcile Einstein’s two theories into a unified whole.

We don’t usually get past Newton in middle school, but this PBS program introduces such a wider and weirder view of the universe that it can help strike the imagination. It also presents complex concepts in an intelligible way.

Blood Falls: Life in Extreme Environments

Blood Falls, Antarctica. Note the tent in the lower left for scale. From the U.S. Antarctic Program.

For millions of years, cut off from the atmosphere and the sun by an immense continental glacier, microbes survived in a lake of salty water under the ice. No air and no sunlight means no oxygen, so the water became anoxic and able to dissolve iron out of the rocks and sediment beneath the lake. But sometimes the lake breaches and the iron rich water comes to the surface where it is exposed to the air once again and the iron reacts with the oxygen to form a red mineral, hematite (rust). A template for life on Europa? Maybe. Blood Falls, Antarctica.

[googleMap name=”Taylor Glacier” width=”490″ height=”490″ mapzoom=”2″ mousewheel=”false” directions_to=”false”]-77.773, 163.37[/googleMap]

Saturn’s aurora borealis

Credit: NASA via Wikimedia Commons

I came across this beautiful animation of the auroras on Saturn. The auroras are caused by charged particles (ions) from the sun, the solar wind of protons and electrons, are focused down onto areas near the poles of a planet by the magnetic lines of a planet’s magnetic field. The ions hit the atmosphere colliding with atmospheric gas molecules like nitrogen and oxygen causing them to become excited and spit out electrons (becoming ions themselves). Molecules are not “happy” when they’re missing electrons so they’ll capture one to become “fulfilled” (fill their outer electron shells). It’s when they recapture electrons that they give off the light that we see as the auroras.

On Earth the auroras are green or brownish-red (from the Oxygen) and blue or red (from the Nitrogen). Saturn’s atmosphere is mostly hydrogen and helium so we’re not quite sure what color its auroras are. The auroras in the animation were colored in by NASA since the camera on the Cassini spacecraft is black and white.

The video clip below gives a nice explanation of auroras.