Where is everybody?

The Fermi Paradox addresses the famous question: are we alone? Statistically, it’s extremely unlikely that Earth hosts the only life in the universe. Most of the universe is (by current knowledge) unreachable to humans. But let’s look at our own galaxy. Many estimates say there should be at least a hundred thousand civilizations in the Milky Way. If we move forward with the assumption that we are not the only life in our own galaxy — I personally don’t consider that a real possibility — that leaves two possibilities. One is that numerous civilizations do in fact exist, but none of them have spread across the galaxy yet. Each civilization is confined to their local planet, or even solar system. Another explanation is that a galactic civilization does exist, but they have not revealed themselves to us, whether it be because they aren’t aware of us or because they’ve decided not to.

Obviously, I don’t have the answer. But I do think it’s likely that one or the other is true. The diameter of the Milky Way has been estimated to be about 100,000 light years. If we are trying to detect another civilization, we’ll have to observe them somehow. There are two challenges here that could easily explain why we haven’t. First, whatever we observe is really the past. If we are looking at a solar system 50,000 light years away, we are seeing what that system looked like 50,000 years ago. So if a civilization there somehow developed spontaneously tomorrow, we wouldn’t see them for 50,000 years (unless they manage to travel closer to us). The second challenge is that we don’t really know what we’re looking for. We know what life looks like here on Earth. Well, we think we do — in reality, estimates are that we’ve discovered 10% of the species that exist in the ocean. But life elsewhere in the galaxy will almost certainly look different than what it does here; life will evolve under different conditions that those on Earth. All we really know to look for is something that seems out of the ordinary.

I do think a galactic civilization could reasonably exist. But can we reasonably expect them to see us? The industrial revolution is a relatively new thing in the history of life on Earth. Any signs “they” might be looking for, unless they have telescopes powerful enough to see the surface of Earth from a different solar system, will only have appeared within the last hundred or two years. These hypothetical outside observers would have to be incredibly close to our solar system to notice; an observer 300 light years away will see a pre-industrial revolution world. Unless they’ve detected one of our spacecraft (which, again, are within our solar system, so may be undetectable unless we have very close neighbors), they probably don’t know we’re here.

My personal opinion is that until we advance as a civilization to the point of interstellar travel, we will be functionally alone in the galaxy. If and when that happens, I believe we will discover other civilizations and they will discover us, but until then all we have is each other.

Where is everybody?

Meet Makemake: The Dwarf Planet Partially Responsible for Pluto’s Demotion

Pluto was discovered in 1930, and was classified as a planet. In 2006, as most of us probably know, Pluto was reclassified as a dwarf planet.

A significant amount of the population, whether justified or not, are opposed to the removal of Pluto from the official list of planets, primarily out of nostalgia for one of the celestial bodies they’d known as a planet their entire lives. So what prompted this reclassification?

In March of 2005, Makemake was discovered. It, along with Eris (discovered in July 2005) and other Kuiper Belt objects, triggered the assembly of the International Astronomical Union. They had a decision to make- expand the current list of planets, or add another classification of celestial bodies. We know how that turned out.

As I was reading about this decision, it occurred to me that I knew very little about Makemake, the dwarf planet that (with Eris’s help) demoted Pluto.

Makemake is roughly two-thirds the size of Pluto. It is slightly dimmer than Pluto, but still bright enough to be the second brightest known object in the outer solar system. Its orbital path extends beyond the farthest reaches of Pluto’s path, yet Makemake orbits closer to the sun than fellow dwarf planet Eris. Despite these similarities to Pluto- size, brightness, orbit- Makemake surprisingly lacks a significant atmosphere (Pluto has one, so we would expect Makemake to have one as well). The dwarf planet’s reddish-brown color led to the conclusion that it has a layer of methane at the surface (remember, no atmosphere).

Another similarity to Pluto is that Makemake has a moon of its own, nicknamed MK 2. This moon wasn’t discovered until April 2015 when it was observed by Hubble’s Wide Field Camera 3.

I personally have quite enjoyed reading about this dwarf planet, and it make me think…If the IAU assembly had voted differently in 2006, we would have more planets (I believe the vote would have upped the number to 12). There would be a good chance we would learn about the would-be new planets nearly as much as we discuss the terrestrials and jovians. We might even devote future exploration missions to these Kuiper Belt objects. What else might be different today if the dwarf planets were just planets?

Makemake and MK 2

A new possibility of life on Mars?

Cavern on Mars

A photograph taken by the Mars Reconnaissance Orbiter (MRO) in 2011 has recently been released, showing what appears to be a sizable underground cavern on the slopes of Pavonis Mons, a Martian mountain standing 46,000 feet tall, higher than Mount Everest.

The possibility of underground caves on Mars is exciting for (at least) two reasons: if there’s any evidence of past or present life on Mars, this would be a good place to look, and it’s possible that such a site could host potential human settlements. The subsurface aspect of the site would protect from the sun’s radiation, and the cave is big enough to make it worth exploring.

A rover to Mars has been scheduled to launch in 2020. This cavern would be a prime target for exploration to evaluate the possibility of human colonization and to search for fossils of any lifeforms that may have been able to thrive beneath the surface of Mars. Either route of exploration could lead to an important discovery about life on Mars: whether it exists or once existed, or whether Mars could be suitable for life in the future.

How did mountains form on Venus?

Surface of Venus

Venus is often described as Earth’s sister planet. Both planets have similar size and densities, indicating somewhat similar core compositions. The primary difference between the two is orbital distance from the sun.

Venus, like Earth, is covered with geological features including volcanoes and mountains. We know how mountains formed on Earth – tectonic plates. Mountains are formed at the boundaries of tectonic plates as a result of the plates colliding and/or moving away from each other.

So on Venus, how were these mountains formed? It is commonly believed that Venus does not currently demonstrate plate tectonic activity. A possible explanation for the lack of observable plate tectonics is the planet’s proximity to the sun. The high surface temperature means it’s extremely unlikely that there is any remaining water in the crust of Venus. Water tends to soften and lubricate rock, which would allow the crust to fracture into plates (like on Earth).

But we have evidence that there should be (or should have been) plate tectonic activity. There are three “continents” on the surface of Venus. On Earth, the continents are a direct result of plate tectonics. The strong presence of volcanoes and lava flows strongly indicate tectonic activity under the surface, beneath a seemingly uniform crust. However, if there were currently active plate tectonics, we would expect the surface of Venus to look much more like Earth, with various ridges and trenches.

So how did these form? There are some impact craters on the surface, but those don’t account for the observed surface features. Were plate tectonics on Venus once an active cycle that’s now obsolete? So far, it remains something of a mystery. Future missions to investigate further are unlikely in the near future, because of the hostile atmosphere of Venus; any visiting spacecraft would likely never be recovered.

An extra fun thought: what would Earth look like without plate tectonics?

Is it possible for a star to be invisible?

One of the things I’ve always been most curious about on the topic of space is: is it possible for something that emits light (like a star) to emit light such as radio or gamma waves but not visible light? If such an object existed, it would be invisible to us, although it could still be detected. But it such an object existed and happened to be traveling on a course dangerously close to our solar system, we might not know to look for it with special instruments because we can’t see it.

Stars are primarily powered by fusion – fusing hydrogen atoms into helium (sometimes other elements are involved, but these are most common). This produces a wide range of light waves, from gamma to radio. Visible light is in between those extremes, so it’s expected to be emitted as well.

Source: Brian Koberlein

The closest thing to a star that doesn’t emit visible light is a black dwarf (pictured above), which has yet to be discovered. Once a white dwarf star runs out of fuel, it theoretically will turn into a black dwarf, emitting no heat and no light. The only way to observe it would be if another object’s emitted light bounced off of it. There are no known black dwarfs; the universe (we believe) has not been around long enough for any white dwarfs to burn through all of their fuel. So, the chances of a massive, invisible object speeding through space towards us (or a similarly invisible approaching alien fleet) are essentially zero.

The Limitations of Space Travel

Let’s just imagine for a moment that humanity eventually advances in technology such that light-speed travel is attainable. The speed of light, roughly 3×10^8 m/s, is the upper limit on travel speed- If light could go any faster, it would.

With light-speed travel, humanity will likely attempt to colonize other planets, for a variety of reasons- curiosity, resource depletion, or even a sense of manifest destiny. Imagine, for a moment, that you are hoping to travel to a habitable planet in the Andromeda galaxy. Andromeda is 2 million light years away. This means that, even if a method of light-speed travel is devised, it would take 2 million years to reach a planet in one of the galaxies nearest to us. For reference, humans have been around for about two hundred thousand years.

Even with an endlessly vast universe, the chances of humans leaving the Milky Way seem to be essentially zero.

Medical News Today

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