Archive for the 'Astronomy' Category

Oct 02 2015

The Problem of Space Junk

Published by under Astronomy

We have been putting stuff into orbit around the Earth, especially low-Earth orbit, for the last 58 years. Space is a big place, so no one probably worried at first that we would start junking it up, but that is exactly what has happened in this short span of time. This is now a serious issue we have to confront.

It’s disappointing, and I hate having one more thing to worry about, but Earth orbit has become so cluttered with debris that it poses a serious risk to our assets in space. Recently former NASA scientist Donald Kessler said in an interview:

“We’re at what we call a ‘critical density’ — where there are enough large objects in space that they will collide with one another and create small debris faster than it can be removed.”

NASA scientists also fear a scenario similar to that portrayed in the movie, Gravity. There were some scientific problems with the movie, but the core idea is valid – there is so much debris in orbit that a collision of two large objects can start a chain-reaction, they will scatter debris which will collide with other objects causing more debris.

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6 responses so far

Jul 14 2015

Why Pluto is Important

Published by under Astronomy

As I write this post we are just minutes away from the closest approach of the New Horizons probe to Pluto, the farthest world we have thus far explored (24 minutes and counting). It’s an exciting moment, not just for astronomy buffs or science enthusiasts, but for humanity. I’m glad to see an appropriate level of excitement among the media and the general public.

Still, a couple of people have commented to me or in my presence that they don’t understand what the big deal is or why this is important, so allow me a moment to explore why I think this is such a big deal.

First, let us not forget what it took to get there. New Horizons is the fastest thing humans ever built. It shot past the moon in 8 hours and 35 minutes, and made a journey of 5 billion kilometers (or 5 terameters, as my friend the Metric Maven would say). On its way it swung around Jupiter to get a gravity assist.

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40 responses so far

Apr 16 2015

Mission to Mars

Published by under Astronomy

Mars is an interesting place. The more we study the surface of the planet with our various robot labs, the more interesting it becomes. This is one of the reasons that it is very enticing to send people to Mars, but there is debate about the feasibility of any mission to Mars over the next few decades.

Life on Mars

Recently the Curiosity rover found evidence that suggests there might be briny liquid water just under the surface of Mars. When the temperature and humidity are just right, salts in the Martian soil could absorb moisture from the air creating a subsurface briny liquid water. This water would then evaporate again when temperatures rise during the day, creating a water cycle.

This would be a harsh environment for life, perhaps not compatible with life as we know it, but extremophiles have surprised us before. It is perhaps more likely that deeper down in the Martian dirt there is more permanent liquid water and more protection from cosmic rays, meaning that life could endure in slightly less extreme conditions.

There are also geological features that suggest recent flowing something, perhaps water bubbling up temporarily from below the ground, and flowing briefly before it evaporates in the thin Martian atmosphere.

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13 responses so far

Apr 02 2015

Lunar Cycle Effects Busted

When I was an intern doing a rotation in the emergency department, on one particularly busy shift a nurse commented (to no one in particular) that it must be a full moon. I habitually look at the moon and generally know what phase it is in (right now it is a waxing gibbous, almost full), and so I knew at the time that in fact there was a crescent moon in the sky. I informed her of this. She gave a disappointed look and then went on with her work without any apparent further thought on the matter.

The episode struck me at the time. It seemed to me that I just witnessed a clear example of confirmation bias – what if it had been near a full moon? That would have confirmed her prior belief in a lunar effect, while this negative correlation was brushed aside and likely did not have any negative effect on her belief. (Although, my interpretation and memory of this event can itself be an example of confirmation bias regarding confirmation bias.)

Belief in the so-called lunar effect, that the phases of the moon exert an influence on human behavior with the most common element being a full-moon inducing extreme behavior, is very common. In my experience it is one of the most common pseudoscientific beliefs I encounter in the general public. One survey indicates that 43% of adults believe in the lunar effect, especially mental health professionals, including nurses.

When someone expresses such a belief to me I often use it as an opening to discuss skeptical principles. While belief in the lunar effect is widespread, it is usually not part of any emotionally held religious or ideological belief. It is therefore an excellent teaching opportunity. One question I like to ask is, “how do you think that works?” The most common answer I receive is probably the least plausible – that the tidal effects of the moon influence the brain because the brain is sitting in water (spinal fluid).

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25 responses so far

Mar 27 2015

Dark Matter Collisions

Published by under Astronomy

The existence of dark matter is one of the coolest science stories of my lifetime. When I was growing up I was in love with pretty much every field of science, but particularly with astronomy, and at that time we had no idea that 85% of the matter in the universe even existed. We now know that the astronomy I was so fascinated with was actually the study of 15% of the matter in the universe. If you count dark energy, which makes up 68% of the universe, then dark matter makes up 27%, and everything that we thought was the entire universe is actually only 5% of the universe.

This story dramatically contradicts every crank and pseudoscientist who tries to tell you that scientists only support the status quo. In my lifetime we discovered 95% of the universe, without any prior theory telling us to expect this result. (Dark matter was hinted at in observations of galaxy rotation, but not generally accepted.) The discoveries were based on unexpected observations, that broke our models of how we thought the universe worked. Scientists met these new ideas with skepticism, but explored them further, and were slowly convinced by mounting evidence. Now dark matter and dark energy are generally accepted – because the evidence convinced the scientists. That is how science works, kids, so don’t believe the cranks.

Dark matter is a powerful idea, even though we currently don’t know what it is, because it not only explains observations that otherwise don’t make sense, it makes predictions. Predictions are the key to scientific progress. They provide the opportunity to test ideas against reality. If an idea does not make any testable predictions, right or wrong it’s just worthless. (Not even wrong.)

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18 responses so far

Mar 20 2015

Titius-Bode Law and Exoplanets

Published by under Astronomy

A recent Washington Post headline reads: Most stars in the galaxy have planets in the habitable zone, according to new research. Some version of this headline was attached to every mainstream media reporting on this story. Not just the headlines were this hyped – most of the time the reporting presented this new research as if this is an accepted conclusion.

I have been following our exoplanet explorations since they began. Like many astronomy enthusiasts, I am particular interested in a few questions – how many planets do stars have on average, what are the typical arrangements of those planets, how typical or atypical is our own system, and how many earth-like planets are out there? We are starting to get a good idea of how many exoplanets are out there – most stars likely have multiple planets.

The other questions are still open at this time. While we are gathering more and more data points, with hundreds of systems now known to have planets, and currently 1,821 confirmed exoplanets. There are a couple thousand more possible exoplanets awaiting confirmation.

This may sound like a lot, but it really isn’t nearly enough data points to answer the remaining questions above. One problem is that we don’t have a thorough survey of each system. We are finding planets that are the easiest to find – those close to their parent stars, and larger planets. Small planets far from their stars would be almost impossible to find given current methods. They would not have a significant gravitational effect on their parent star, and even if they happened to transit their star they would probably have an undetectable effect on the light from that star. Also, with periods of hundreds of years, it would take hundreds of years to confirm them by the transit method.

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12 responses so far

Feb 02 2015

Gravity Waves and Science Self-Correction

Published by under Astronomy

In 2011 scientists tentatively reported that they may have detected neutrinos traveling faster than the speed of light in apparent contradiction to the theory of relativity. By early 2012 the technical error that led to the apparent discovery was revealed.

Also in 2012 scientists reported that, using the Large Hadron Collider, they probably found the Higgs boson, the particle responsible for mass. However they were still not completely sure so they kept testing, and then last year they announced that indeed they did identify the Higgs as predicted by the standard model of particle physics.

In March of 2014, in what was definitely the biggest science news story of the year scientists reported detected gravity waves from the Big Bang, confirming the theory called the “inflationary universe.” The discovery was hailed as a “smoking gun.” at the time wrote:

If it holds up, the landmark discovery — which also confirms the existence of hypothesized ripples in space-time known as gravitational waves — would give researchers a much better understanding of the Big Bang and its immediate aftermath.

In those four little words, “if it holds up,” lies the essence of science. This is just a sample of recent big science news stories that reveal the process of science – skeptical questioning of all claims and testing those claims against objective evidence.

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Jan 16 2015

Trans-Neptunian Objects

Published by under Astronomy

My mental map of our solar system has evolved over the years, as I have learned more about astronomy and as astronomers have learned more about our solar system. When I was younger that mental map ended with Pluto, the ninth and outermost planet of our system. I then learned that Pluto’s orbit takes it within the orbit of Neptune, and from 1979 to 1999 Neptune was actually the furthest planet.

My mental map expanded greatly when I learned about the Kuiper belt and the Oort cloud (I can’t remember now which one I learned about first). The Kuiper belt is a doughnut shaped region of space beyond Neptune that contains many small icy worlds. The Oort cloud is a spherical shell farther out still that contains small chunks of dirty ice and is likely the source of many long period comets that sometimes fall into the inner solar system. Short period comets likely come from the Kuiper belt.

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Jul 22 2014

Aliens are Sinners

To paraphrase Carl Sagan: in one unremarkable galaxy among hundreds of billions, there is an unremarkable star among hundreds of billions of stars in that one galaxy. Around that star revolves a world with life. Some people who live on that world believe they are the center of the universe.

Sagan nicely puts into perspective how absurd it is to believe, given our current knowledge of the cosmos, that we are the center of all things, either physically at the literal center, or metaphorically as in, we are the most important things in the universe. This is a childish view, held by our ancestors because they couldn’t know any better. Science, as Stephen Gould noted, is partly a process of smashing pillars of human narcissism. Neither the earth, nor our sun, nor our galaxy are at the center of the universe. The universe, it turns out, has no center. Neither are humans at the pinnacle of the evolutionary tree – we are just one twig, and every other twig has just as much evolutionary history behind it as we do.

Humans are certainly the most encephalized species on the planet, with by far the most advanced culture and technology, so we are special in that sense. Every time, however, scientists believe they have nailed down something that is unique about humans, some researcher finds that chimps (our closest cousins), or even other species, can do it too. We are part of the animal kingdom, part of this physical world, the result of natural processes that seem ubiquitous throughout the universe.

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41 responses so far

Jun 20 2014

Inflation Evidence Questioned

Published by under Astronomy

A critical part of skeptical outreach is teaching the public about how science works. Surveys of scientific literacy generally have dismal outcomes, but they also generally focus on knowledge about the findings of science, and not so much on the process of science. My personal experience from engaging with the public in multiple venues over decades is that those who are critical or suspicious of science generally are laboring under a gross misunderstanding of how science operates.

Actually it’s not quite accurate to talk about “science,” and that is not how I think about or evaluate scientific claims. Rather, the global scientific community has a certain culture and norms of acceptable behavior. Each country, however, has their own subculture and may have problems or failings specific to them. China, for example, apparently can only publish positive studies about acupuncture, betraying a national bias that calls into question any acupuncture study originating from that country.

Each scientific discipline also has its own subculture. Some professions and specialties are more rigorous than others. Further, each institution, lab, and researcher has their own culture and behavior.

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