I probably shouldn’t ask this, but do you believe the Earth has been visited by intelligent extraterrestrials?  Do you think we are STILL being visited, or “watched”, by aliens?  Do you believe an alien culture was instrumental in the development of our culture on Earth?

We’ve all heard the theory that aliens visited the Earth in antiquity, and that they were regarded as gods.  In May of 2008, the Vatican even agreed that there was a possibility of intelligent extraterrestrial life, and that it (the Church) was okay with that belief.  Wow.  That would’ve got you burned at the stake a few centuries ago.

A very interesting read in 1968.

In 1968 Erich von Danikan published Chariots of the Gods, an international best-seller which hypothesized that ancient technologies and ancient religions where based on alien visitation.  Many of the artifacts von Danikan presented in his book have since been proven by science as having terrestrial origins, but many more are still puzzling and intriguing.

Mayan tomb image. Has been interpreted to show a humanoid figure within a spacecraft.

Jomon statue - has been interpreted as a figure of an ancient astronaut.

The issue heats up when you start looking at archaeological remains.  They’re digging up evidence of civilizations much older than we had thought existed.  The underwater remains are especially intriguing.  Proponents of the theory say that there is evidence of ancient alien visitation in the archaeological record.  I don’t know about that, but I do know that some of the artifacts unearthed are thrilling in their mystery.  Take, for example, the Antikythera Mechanism.

Main fragment of the Antikythera Mechanism - they salvaged three fragments.

That’s mind blowing, in itself.  In fragments, this was discovered in an ancient shipwreck in 1901.  It’s been studied for years, and is now known to be the remains of a complex and sophisticated scientific calculator used to predict the positions of celestial bodies.  This machine has been dated at about 150-65 BCE.  You can go here and watch a computer reconstruction of the device, or go here to the website devoted to research on the device.

Does this mean we have been visited by an alien culture?  I don’t know, myself, but I’d sure like to visit some of those archaeological sites.  What do you think about the issue?  Do you think there is anything in the archaeological record that points to an alien culture?  Do you think we’ve been visited by aliens?  Do you think we’re being watched, or monitored, by an alien intelligence?  Why?

The Pleiades cluster enlargement from the poster, click to see a small version of the poster itself. Credit: Ashland Astronomy

Stars of the Northern Hemisphere is the title of a poster available from Ashland Astronomy Studio.

If you are interested in the night sky but don’t know quite where to begin this poster will come in quite useful.  You probably already have a pair of binoculars so using the poster you will quickly be able to identify some great targets.

Along with Over 2,400 stars including the locations of stars with their own planets (extra solar planets), the poster includes enlargements of the Pleiades (above) and Hades star clusters too. If you’ve never looked at the Pleiades through binoculars do it you will be amazed at what you see.  You will be amazed.  Hint, use a lawn chair/recliner/ or air mattress to be comfy.

The constellations, asterisms and notable stars are all named in this 36 by 24 inch poster which is one of the best ones on the market and at a very reasonable price.  So whether for a classroom, bedroom wall or especially to have handy to find interesting things to see in the night sky, this poster is well worth owning.

Visit Ashland Astronomy for more.

I thought this was interesting about Mars’ atmosphere.  It makes sense, but I didn’t think there would be this much change.

NASA/Opportunity - panoramic view of the Victoria Crater on Mars (true color image)

MOFFETT FIELD, Calif. — NASA’s Mars Reconnaissance Orbiter (MRO) has discovered the total amount of atmosphere on Mars changes dramatically as the tilt of the planet’s axis varies. This process can affect the stability of liquid water if it exists on the Martian surface and increase the frequency and severity of Martian dust storms.

Researchers using MRO’s ground-penetrating radar identified a large, buried deposit of frozen carbon dioxide, or dry ice, at the Red Planet’s south pole. The scientists suspect that much of this carbon dioxide enters the planet’s atmosphere and swells the atmosphere’s mass when Mars’ tilt increases. The findings are published in a report in the journal Science.

The newly found deposit has a volume similar to Lake Superior’s nearly 3,000 cubic miles. The deposit holds up to 80 percent as much carbon dioxide as today’s Martian atmosphere. Collapse pits caused by dry ice sublimation and other clues suggest the deposit is in a dissipating phase, adding gas to the atmosphere each year. Mars’ atmosphere is about 95 percent carbon dioxide, in contrast to Earth’s much thicker atmosphere, which is less than .04 percent carbon dioxide.

“We already knew there is a small perennial cap of carbon-dioxide ice on top of the water ice there, but this buried deposit has about 30 times more dry ice than previously estimated,” said Roger Phillips of Southwest Research Institute in Boulder, Colo. Phillips is deputy team leader for MRO’s Shallow Radar instrument and lead author of the report.

“We identified the deposit as dry ice by determining the radar signature fit the radio-wave transmission characteristics of frozen carbon dioxide far better than the characteristics of frozen water,” said Roberto Seu of Sapienza University of Rome, team leader for the Shallow Radar and a co-author of the new report. Additional evidence came from correlating the deposit to visible sublimation features typical of dry ice.

“When you include this buried deposit, Martian carbon dioxide right now is roughly half frozen and half in the atmosphere, but at other times it can be nearly all frozen or nearly all in the atmosphere,” Phillips said.

An occasional increase in the atmosphere would strengthen winds, lofting more dust and leading to more frequent and more intense dust storms. Another result is an expanded area on the planet’s surface where liquid water could persist without boiling. Modeling based on known variation in the tilt of Mars’ axis suggests several-fold changes in the total mass of the planet’s atmosphere can happen on time frames of 100,000 years or less.

The changes in atmospheric density caused by the carbon-dioxide increase also would amplify some effects of the changes caused by the tilt. Researchers plugged the mass of the buried carbon-dioxide deposit into climate models for the period when Mars’ tilt and orbital properties maximize the amount of summer sunshine hitting the south pole. They found at such times, global, year-round average air pressure is approximately 75 percent greater than the current level.

“A tilted Mars with a thicker carbon-dioxide atmosphere causes a greenhouse effect that tries to warm the Martian surface, while thicker and longer-lived polar ice caps try to cool it,” said co-author Robert Haberle, a planetary scientist at NASA’s Ames Research Center in Moffett Field, Calif. “Our simulations show the polar caps cool more than the greenhouse warms. Unlike Earth, which has a thick, moist atmosphere that produces a strong greenhouse effect, Mars’ atmosphere is too thin and dry to produce as strong a greenhouse effect as Earth’s, even when you double its carbon-dioxide content.”

The Shallow Radar, one of MRO’s six instruments, was provided by the Italian Space Agency and its operations are led by the Department of Information Engineering, Electronics and Telecommunications at Sapienza University of Rome. NASA’s Jet Propulsion Laboratory in Pasadena, Calif., manages the MRO project for NASA’s Science Mission Directorate at the agency’s headquarters in Washington. Lockheed Martin Space Systems in Denver built the spacecraft.

A glorious image of the southern sky from the ESO. Click for larger, full res link below. Credit: ESO/Y. Beletsky

That about sums up the description of this image as far as I am concerned.  Want a desktop of this?  Even if you don’t, head over to the ESO and look at the full res/sized picture just the same – it is just stunning.

Oh you want a better description?  This from the ESO:

Deep in the Chilean Atacama Desert, far from sources of light pollution and other people-related disturbances, there is a tranquil sky like few others on Earth. This is the site for the European Southern Observatory’s Very Large Telescope, a scientific machine at the cutting-edge of technology.

In this panoramic photograph, the Large and Small Magellanic Clouds — satellite galaxies of our own — glow brightly on the left, while the VLT’s Unit Telescope 1 stands vigil on the right. Appearing to bridge the gap between them is the Milky Way, the plane of our own galaxy. The seemingly countless stars give a sense of the true scale of the cosmos. Every night ESO astronomers rise to the challenge of studying this vista to make sense of the Universe.

This awe-inspiring image was taken by ESO Photo Ambassador Yuri Beletsky. Born in Belarus, Yuri now lives in Chile where he works as an astronomer. The dark skies above the Atacama Desert provide him with splendid opportunities to reveal the majesty of our cosmos, which he is keen to share.

Wait!  Come back!  This isn’t nearly as confusing as it sounds.  You’ll have this down cold in five minutes.  Really.

Okay, let’s say astronomers have just found a planet circling a star 50 light years away from us.  That’s not too much of a stretch; that’s the distance 51 Pegasi b sits out from the Earth.  Anyway, back to our new planet.  Our scientists announce that the planet has hydrogen, oxygen, and nitrogen in its atmosphere.

Emission spectrum of Hydrogen

Emission spectrum of Iron

Cool!

Wait… what?

How did they do that?  How do they know what’s in a planet’s atmosphere, short of going there and taking a good, solid sniff?  For that matter, how do they even know for certain the planet has an atmosphere?  It takes some serious equipment to be able to find the planet, much less its atmosphere.

(Absorption lines in the Solar Spectrum)

You know how these planets are being discovered, right?  One very good way is to study the light intensity of a star and watch for little dips in the level which would signify something passing between you and the light source, blocking out part of the light you see.  Bingo.  Once a planet has been found, you watch the light as it passes close to your object, and if there is an atmosphere there, it will change the “tone”, or “quality” of light you’re perceiving.  Just a tiny bit… but enough.  That’s spectrophotometry; the image and comparison of various spectra for scientific analysis.

The concept itself isn’t difficult to master, once you get beyond the formidable name.  You know that light passing through water looks different depending on what’s in the water.  Well, an atmosphere is nothing really except an extremely… puffy… fluid.

Diagram by Kevin Saff - this shows how carbon in the environment impacts carbon levels in the atmosphere

Now, you know that every element has its own “signature” on the light spectrum, right?  We have applications for that in every day science here on Earth.  You’re especially familiar with the concept if you follow forensics.  That’s how you tell whether or not your victim has traces of arsenic in his/her body; arsenic has its own “signature” on the light spectrum based on what’s absorbing or reflecting light.

You take this tiny bit of light that’s passed through the atmosphere of your distant planet, separate it out (like the way a prism separates out visible light), and you have the signature of everything that’s in your planet’s atmosphere.  It’s as easy as if we were reading a list of ingredients; in fact, that’s in essence exactly what we are doing.

The science doesn’t stop here, of course.  If we knew that certain life forms (like… ours, maybe?) leave chemical “markers” on the atmosphere, markers that are there only in the presence of this particular life form; and then we find those markers in the atmosphere of another planet…

… wow.