UFOs and the 2%

Being an amateur astronomer, UFOs are close to my heart. I have been asked by countless people what I think of UFOs. On the Internet, it is not hard to find claims that UFOs are evidence of a hostile alien invasion, benevolent beings here to save us from ourselves, or that there are multiple species all here competing with each other for our loyalty. It is clear people are truly seeing strange things in the sky and others report first hand encounters. So the question is 'what should believe?'

There is no denying that people see strange objects in the night sky on a regular basis. Someone recently told me a story of a object he had seen with a group of people that reportedly would move in one direction, stop, then completely change direction and continue moving along. Even I have seen a UFO. I was just starting out as an amateur astronomer.  It was twilight, and to my amazement I saw a bright object hovering over a nearby lake. The object was flashing white red and blue. I was completely taken aback and at a complete loss for an explanation.

There countless stories like the ones above. Still, I have heard even dedicated UFO proponents admit that probably 98% (or pick your own number) of sightings and encounters are hoaxes or misidentified normal phenomena. It is those 2% of sightings that we can't come up with a explanation for, that they believe represent the real encounters.

The problem with this argument is that you are moving from an unknown (hence unidentified flying object) to an answer (aliens exist) without any further evidence. Scientists work with unknowns all the time. They may have a hypothesis that they are trying to gather evidence for, but without that evidence, it remains an unknown. Law enforcement does the same thing. If a case can't be solved, they simply label it unsolved. They don't assume that aliens did it.

With that said, I want to look to see if there is any reason that this small percentage of cases might go unsolved if aliens are not visiting our planet. Some of them probably are hoaxes or hallucinations. As Randall Munroe of xkcd shows above, it doesn't take many people misunderstanding something they seen in the night sky to make a lot of UFO stories. In may other cases, we just don't have enough information to find any answer.


If you want to say aliens exist you need evidence. UFOs, even those cases that are never solved, just don't cut it. Take my story above. I see no fundamental difference between mine and many others out there, except I found out what it was. I stared at the object over the lake for hours off and on. As it slowly rose in the sky, its colors settled down into the bright familiar glow of the star Sirius. The wild colors were probably caused by a nearby fire or other air pollutants. Still if I had reported it as a UFO, without some key details, no one could have ever proven what that object was. I doubt we will ever solve all UFO cases but that doesn't bother me one bit. What gets me going is the trill of finding an answer, one I can explain and defend, and growing my understanding of how the universe really is.

Scientific Unknowns: Life on Titan?

Sunlight reflecting of one of the lakes of Titan
Image Courtesy: NASA/JPL/University of Arizona/DLR

Of all the places we look for life in the solar system, there is one that has captured my imagination more than any other. Maybe it is because of this obscure moons weirdness, or the possibly of an entirely new biology. Either way I could not discuss life in the solar system and leave it out. So what plausibly and evidence is there for life on Saturn's largest moon? The answer may surprise you.

Here on Earth all life requires water. Water makes a great solvent. This simply means a large variety of different molecules can be taken up by the water. Suspended in liquid water, those molecules can move around to do the things of life. This works great here on Earth and water may even be a good solvent for possible life on Europa. Titan however, is a balmy -290 ^oF, putting water out of the picture. Luckily Titan is covered with another liquid that may be able to fill the same role as water, liquid methane. I need be clear in saying that we have no idea if life can form in liquid methane. Maybe it forms easier in methane than it does in water. While there are some good reasons to think water may be the liquid of choice, we simply don't know. This is what make Titan such an interesting world to explore.

An infrared image of Titan showing Titan's Northern Lakes
Image Courtesy: NASA/JPL/Space Science Institute

So now we have a feel for the plausibility of life on Titan, but what about the evidence? Often in science you test a hypothesis by building a model that produces predictions. Then you test those predictions to see if the model reflects reality. In 2005 a team of astrobiologists published a paper making some suggestions about what we might expect to see if some sort of methanogenic life were enjoying the orange haze of Titan. In 2010 data from the Cassini Huygens probe matched those predictions. So what does that mean? Well it means that this model deserves strong consideration. That said, we should not be quick to accept any claim of alien life. There are a huge multitude of processes not involving life that can change the chemistry of an atmosphere. This evidence is a exciting starting point, but it is not proof.
So when it comes to Titan, even more so than Mars or Europa, I can only say we have no clue if there is any life present. Titan is a moon we have only recently gotten a good look at. Astronomy has a history of dismissing early speculations of life with future observations. Will that pattern hold true on Titan? We need more scientists and more spacecraft to find the answer. Right now I can only say that I don't know, but that I am extremely excited to see the discoveries made as we hunt down the solution.

Scientific Unknowns: Life on Europa

Europa as seen by the Galileo Spacecraft. 

Credit NASA/JPL/DLR

When we think of aliens we often think of a place similar to Earth. We think of creatures with similar body plans and similar needs. But what about the possibility of creatures that have never seen the Sun? This is the kind of life that could be hiding on Europa, Jupiter's fourth largest moon.

There are two sides to every claim, plausibility and evidence. Some claims, like many new medical drugs, start with a high plausibility but the evidence never bears them out. Others, such as quantum mechanics, start with low plausibility but the evidence becomes overwhelming until they are accepted. Right now, to my knowledge, there is no evidence of life on Europa. What makes it exciting, however, is how plausible it is that life could exist there.

Europa's entire surface is covered with ice. Located almost a half billion miles from the Sun, there is nowhere near enough heat from the sun to melt Europa's ice covered surface. Still many, if not most, scientists agree that there is likely a ocean under that ice. As Europa orbits around Jupiter, it is squeezed and stretched. This is what creates the cracks you see on the surface. This also heats Europa's core in the much the same way playing with Silly Putty will warm it up over time, creating a layer of liquid water. There is a lot of debate between scientists on how thick this ocean is. Right now, it seems likely that the ice is tens of kilometers thick with an ocean that is between 25 to 100 kilometers thick. So the question is could anything survive in the ocean?

A cutaway view showing Europa's interior. Notice the
inner rocky core surrounded by liquid water and capped
 off an outer layer of ice.
Credit: NASA/JPL

If there is any life in Europa's ocean, it have had to have formed and survive with no sunlight. The ice above this ocean is just too thick to allow in enough sunlight for any organism to use that as a source of energy. So scientists have looked to the Earth for creatures that can survive without the Sun. Probably the most similar environment to Europa here on Earth is the ocean under the Antarctic ice. When scientists have drilled into the ice there we have found life. In fact scientists have found entire colonies of organisms called black smokers that live in some of the harshest conditions on the Earth. These organisms live off of hydrothermal vents at the very bottom of the oceans where there is no light at all. Some scientists have even speculated that this is where life on Earth originated in the first place. These unique adaptations of life here on the Earth make it reasonable to think similar creatures could survive on Europa.

A hydrothermal vent on the
Mid-Atlantic Ridge. Credit NOAA

So when it comes to life on Europa we have a really good story. We have solid reasons to think the ocean is there and that life could possibly survive in that ocean. What we are missing is the evidence. A detailed study of Europa is high on NASA's priority list, but without the proper funding it could easily still be more than a decade away. At this point, we don't have the evidence to say if life exists on this icy moon or not. I hope in my lifetime a spacecraft arrives at Europa and drills through that ice. What we find in that ocean could change how we think about ourselves and the universe we live in.

Alien Update

I want to quickly revisit the alien meteorite from last week. Here are some good links to take a look at if you are curious.

I was wondering what NASA was going to say about this. Here is their official statement. If this research really carried some weight, I would expect NASA to be publicizing it to no end. Instead, they are distancing themselves.

This is the best review of the science in the paper I have seen so far. They also a fairly good job of reviewing the journal itself.

I know I linked to Bad Astronomy before but I am going to do it again. He does a nice job laying out the criticisms made other places in a very understandable way.

After reading all of the follow-up here and other places, my original opinion still holds. The science here is just not nearly enough to prove the claim being made.

Aliens Exist: Proof Pending

Last week I mentioned how I wanted to do some posts talking about the possibility of life in the solar system. Well, apparently that is going to be a waste of time, since this Saturday Yahoo News released an article reading in its first line "Aliens exist, and we have proof." Fox News was no better with their first line "We are not alone in the universe -- and alien life forms may have a lot more in common with life on Earth than we had previously thought." How much did we think we have in common with alien life forms before? Anyway, both articles discuss a paper done by NASA astrobiologist Dr. Richard Hoover who claim that he has found evidence for fossil alien bacteria in a meteorite. With a news story like this spreading across the Internet, I couldn't help but do some digging.

First, I went looking around my usual astronomy news sites. As of Sunday evening, I couldn't find a thing mentioning it. This is really peculiar and made me that much more skeptical. The one article I could find was on Bad Astronomy by Phil Plait. It is a good review of the paper and makes several of the same points that came to mind for me. Still, the vast under-reporting of this breakthrough in the specialized media is a point I think is worth mentioning. If you ever see something in the mainstream media, look to see what the people who deal with that subject on a regular basis have to say. While not always true, I have found that breakthroughs tend to go from the specialized media to the mainstream; nonsense tends to flow the opposite way.

With no luck in the space news, it was time to go to the paper itself. The largest problem this paper faces is in that pesky relationship between claim and evidence. If you are going to claim extraterrestrial life, you need a mountain of evidence to back you up. Dr. Hoover works hard in the paper to rule out any earth-based contamination. He is quoted in the journal press release with the following.

"What is both exciting and extraordinary is although many of the bacteria resemble and can be associated with generic species on Earth, there are others which are completely alien. Neither I nor other experts who have seen the evidence have any idea what these creatures might be."

It could be true that no one who has studied the rock has been able to identify the bacteria inside. This does not mean however, that they are necessarily alien. In the paper itself, he tries to use the specific chemistry to the meteorite and the "fossils" to rule out abiotic causes and earthly contamination. I do not have the technical knowledge to delve into these details, so it will be interesting to see what the editors of paper said when those are released.

In the end, I think this paper falls short. I want to see how the scientific community responds over the next few days and what, if anything, comes of this. That is part of what makes science so interesting. Now the paper is published and the real critique can start. For now I remain unconvinced but eagerly await to hear what story will come from this.

Scientific Unknowns: Life on Mars

The question of how much life there is in the universe is one of the most fundamental questions in astronomy, and possibly all of science. While we are just now on the brink of finding Earth-like planets around other stars, the possibility of life existing on planets very different from our own still remains. While scientists have dismissed the old notions of grand civilizations on Venus and Mars, there is tantalizing evidence of microbial life throughout the Solar System. This is a first in a series of posts I will do over the next few weeks looking at some of the top contenders.

Of all the places we look for life in our solar system, none seems to have the mystique of Mars. The search for life on Mars has deep historical roots. Percival Lowell infamously reported his evidence for a grand civilization on Mars with a grand irrigation network. This and other stories firmly set Mars as the home of extraterrestrials in science fiction. While scientists are no longer searching little green men on the surface, microbes on the red planet have become hot topic of debate. Mars surface is bathed in radiation that would likely prevent anything from living on its surface. Liquid water also can no longer exist on the surface of Mars. These both come from the fact Mars lacks the thick atmosphere and magnetic field we have on the Earth. So planetary scientists are now searching for microbes under the surface of mars. For those scientists there are three main lines of evidence.

1. Recently, there has been a growing consensus that a few billion years ago, Mars had at least a some running water on its surface. The Earth appears to have developed life fairly quickly once the oceans formed. The thinking goes that if Mars had conditions similar to that of the early Earth, it is reasonable to assume that it would have developed life in a similar way. Mars has changed so much over the last few billion years to become the dry and harsh world it is today, that it is not surprising that we don't see the abundance of life we now have on the Earth. This idea gives hope that possibly some microbial life was able to take hold on Mars during the planet's youth and maybe still be surviving under the surface.

2. If life ever existed on Mars, we could maybe find evidence of it the same way we find evidence of past life on the Earth: fossils. It is well accepted that large impacts from meteorites on the surface of Mars can lob chunks of the Red Planet into space. The Sun can then pull those into the more inner part of the solar system where they collide with the Earth. What is controversial is a claim made by a group of scientists in 1996 that one such Martian meteorite contained a fossilized bacteria. If true, this would be sure evidence of at the very least past life on Mars. After 15 years of research however, the scientific community is still far from a consensus.

In science, extraordinary claims require extraordinary evidence. Life on Mars is certainly an extraordinary claim. Unfortunately, the evidence has yet to match. Without going into extreme technical detail, the core issue is whether or not the meteorite in question, Martian meteorite ALH84001, could have plausibly formed without life. Scientists look at a multitude of characteristics, mostly based around the various minerals including their isotopes, distribution, and texture. I think it is safe to say that our current results have been inconclusive. There are scientists with strong points on either side. In the end, the evidence is just not there to make a solid decision.

3. The final hint of life on Mars is methane. This is something I touched on briefly in the past and the basic story is this. The chemistry of Mars atmosphere is such that methane breaks down over time. We have found large quantities of methane in Mars atmosphere, so we know it must be replenished by some ongoing process. At this point all we have is the observation of the methane itself, and speculation about what is causing it. The reason people get excited is because one of the ways methane is produced here on Earth is by bacteria. Scientists, however, are also quick to point out that we know of geologic processes that can produce methane in the quantities we seen on Mars. Again, this line of evidence seems tantalizing, but non-conclusive.

So, what is the final story for Mars? I have to say that, while there is good reason to continue looking for microbes under the surface, we can't say we know they will be there. Either we will see exciting geology or revolutionary biology. Regardless, Mars continues to be a place worth exploring with mysteries lurking just beneath the surface.