There are many extremophiles on Earth, some that roam the Sahara Desert and come out only for the hottest parts of the day and some that scale the coldest parts of the arctic. Extremophiles are an interesting phenomenon with applications to discovery of other life in the universe. If these organisms can survive in these extreme circumstances on Earth, who is to say that there are not similar organisms capable of survival in extreme conditions in space? Surviving in space is certainly a different feat than the Sahara or arctic, as space conditions are unpredictable, reaching extreme high and low temperatures and pressures. There are however, polyextremophiles, such as water bears which can survive a variety of extreme conditions. Water bears have even survived exposure to space, including radiation, solar winds, and an oxygen deprived vacuum. The existence polyextremophiles leads us to question if life on other planets is more likely than we think, given the evidence that some unique organisms can survive in such extreme conditions.
If we think for a moment about the size of our universe and how many Earth like planets orbiting a star much like our Sun, it doesn’t take long to begin to wonder, where is everybody else? This is called the Fermi Paradox. Some estimate that there should be about 10 quadrillion (10 million billion) intelligent species in the universe, so why do we not have any evidence of even just one other intelligent species. While there are various possible explanations for this paradox, one especially interesting one is called the Great Filter theory. This theory suggests that before an intelligent species can reach the point of interstellar colonization (Type III Civilization), it must accomplish a difficult evolutionary leap that almost all species fail to achieve. So, what does this theory suggest about our species? The first of three possible options is that we’re the rare species that managed to already make the almost impossible evolutionary leap.
This would mean that we are already on our way to achieve interstellar colonization, and that it is simply a matter of time before we do so.
The second possibility is that no civilization has reached the Great Filter yet, and that we may have the necessary resources to achieve Type III Civilization.
One objection to this option is, if the universe has been along for such a long time before our civilization developed, how could we be the first to achieve Type III Civilization? One explanation is that the universe is only now capable to sustain life long enough for it to develop. This is backed by our observance of gamma-ray bursts in distant galaxies, which would prevent life from developing.
The third and final option for where we stand in the Great Filter theory is that we lie before it.
This means that it is only a matter of time before we hit the metaphorical brick wall that stopped all other instances of intelligent life from achieving interstellar colonization.
We usually think of the Sun as providing us with only a few things such as light and heat, however, the Sun’s impact on Earth extends far beyond that. One additional way that the Sun impacts Earth is through the spewing of products of the Sun’s atmosphere directly toward Earth. The Sun releases electrically charged clouds of hot gas out of its atmosphere, and although most of it doesn’t affect us due to Earth’s magnetic field, we still experience some of the effects of the Sun’s atmosphere. The effects of Sun’s atmosphere on Earth is commonly known as “space weather”. Space weather causes some incredible phenomena on Earth, such as the Northern and Southern Lights, as well as Aurora Borealis and Australis. Space weather from the Sun flows down the magnetic field surrounding the Earth, making its way towards the North and South poles. The charged particles released by the Sun’s atmosphere glow in various colors, which can be seen clearly from Earth’s surface near the North and South poles.
Although space weather has some positive effects on Earth, such as the release of charged particles that glow in different colors as they hit Earth, it can cause serious problems if not carefully monitored. Space weather can cause disruptions in infrastructure such as aviation, power grids, and navigation systems. Infrastructure both on Earth’s surface and in nearby space is vulnerable to the effects of space weather. Recently, as we learn more about how space weather effects human infrastructure, precautions are being taken to prevent future damage. The Joint Research Centre (JRC) is currently campaigning to reduce the negative impacts of space weather, by implementing more advanced space weather detection systems and advancing research in how to enhance space weather forecasting abilities.
The Kuiper Belt is a disc in the solar system, extending from Neptune’s orbit to 50 AU from the Sun. The belt is like an asteroid belt, but it is far larger and more massive, containing many small bodies and remnants from the formation of the solar system. As expected, most objects in the Kuiper Belt tend to stay in it, however, there is evidence that an object from the Kuiper Belt made its way out of the belt and inside of Neptune’s orbit. This object is known as Triton, and is one of Neptune’s moons. Triton was discovered in 1846, only 17 days after Neptune itself was discovered. Triton, if not taken into Neptune’s orbit, would have been classified as a dwarf planet and actually has a composition quite similar to Pluto. Triton has many interesting qualities, the first being that it is the only known moon in the solar system with retrograde orbit. This means that Triton orbits Neptune in the opposite direction that Neptune spins. Triton is similar to most moons on the outskirts of the solar system in that it has a rocky, icy composition, however, it is very unique given that it is geologically active. Its geologically activity causes a phenomenon known as cryovolcanism, where geyser-like volcanic vents break through the crust and spray nitrogen gas. Due to our lack of knowledge of Triton’s past, it is hard to say with certainty, but some astrobiologists even speculate that Triton may have water under its icy surface.
For a long time, we were generally unsure of how Earth’s moon originally formed, and there were a few popular theories which were later disproven. Below are original theories about the formation of the Moon and how they were disproven:
This theory is based on the fact that the chemical composition of the Moon is somewhat similar to that of Earth’s mantle. The theory proposes that in the early days of the solar system, the Earth was spinning so quickly that a piece of it was flung off of one of its outer layers, and eventually went into orbit around the Earth. This theory does not hold up because there is no “fossil evidence” of the rapid spinning at the basis of this theory.
This theory suggests that the Moon was a particular object flying through space that got captured by the Earth’s gravitational field, thus sending the Moon into orbit around the Earth. This theory does not hold up given the likelihood that the Moon was formed in some way from the Earth (similar chemical composition) and because it is unlikely that the Moon slowed down enough to become captured by Earth’s gravitational field.
This theory suggests that the Earth and Moon were formed individually and at the same time, from the nebula that formed the solar system. This seems to make sense given that the Earth and the Moon have similar composition, however, they would have to have a far more similar composition for this to be possible (the Moon should have an iron core, but it does not).
The theory which is widely accepted today is called the Giant Impactor Theory, and suggests that the Moon was formed through a collision between the newly formed Earth and a rock about the size of Mars. Astrophysicist Mastrobuono-Battisti simulated collisions in the early solar system and found that most simulations produced 3 to 4 rocky planets comparable to Earth. Around 30% of the time, the composition of one planet was very similar to that of the last planet that collided with it, providing additional evidence in favor of the Giant Impactor Theory.
We commonly think of asteroids simply as left over debris from when the planets were formed, but researchers believe that we will be able to harness resources from them within the next 10 years. The most common type of asteroid, C-type, contains up to 20% water as well as various metals. The presence of water has a potentially useful application, that is to be converted into rocket fuel. If this practice is perfected, rockets will have a far less restricted distance that they can travel, allowing for exploration farther away than has ever been done before by humans. In addition to water, platinum group metals, which are valuable and have other useful applications, are also found in many asteroids. Planetary Resources, an asteroid-mining company based in Washington, believes that they will be one of the first to contribute to the just started asteroid-mining market. Planetary Resources has already launched their first probe into space and believes that they might be the first to use resources from asteroids, in as little as 5 years. These new developments do have the potential to create problems, and there will need to be some sort of organizational system in place before the market for asteroid-mining grows too large. While harnessing resources from asteroids complies with the Outer Space Treaty of 1967, Congress is looking into legislation regarding asteroid-miners’ property rights.
An interesting video about the basic elements of asteroid-mining can be found here.
The first thing that comes to mind when thinking about tides is the lunar tides that create 2 high and low tides each day. This is due to daily rotation of the Earth, which causes the Moon to effectively move around the Earth every day. The Moon’s gravitational force pulls the water from the sides of the Earth towards the part that is facing the Moon, which creates higher water levels on the side of the Earth facing the Moon, as well as the side opposite the Moon. The moon, however, is not the only celestial body that has a gravitational pull on the Earth. While the Sun is significantly more massive than the Moon, it is much farther away, so its gravitational pull on the Earth is lesser than that of the Moon. Since the positions of the Sun and Moon are not always perfectly aligned relative to the earth (they rarely are), there is also a cycle of high and low tides affected by the position of the sun. These are called spring and neap tides. Spring tides occur when the Sun’s gravitational pull is in the same general direction as the Moon’s, causing high tides to be higher and low tides to be lower. Neap tides occur when the Sun’s gravitational pull is in the opposite direction of that of the Moon, causing high tides to be lower and low tides to be higher. Another interesting occurrence is the Proxigean Spring Tide, which occurs when the Moon is unusually close to the Earth during a spring tide. This occurrence creates a “super tide” where especially high and low tides occur.