Many scientific theories attempted to explain the source of the Sun’s energy, and the very first hypothesis involved some explanation pertaining to chemical reactions and gravitational collapse. Chemical burning, however, was ruled since no chemically burning substance like wood or gasoline can account for the Sun’s enormous luminosity. As for gravitational collapse, the conversion of gravitational potential energy into heat would only allow the Sun to shine (produce enough energy) for 25 million years. This theory was scratched thanks to geological research, which proved that the Earth is much older than that (~4.5 million years).
Ultimately it was the development of nuclear theory that revealed the truth. The Sun generates immense amounts of energy from nuclear fusion reactions in its core. When Hydrogen is converted into Helium, some mass is lost in the process. This fraction of mass is transferred into energy. This amount of energy is identified by Einstein’s equation: E=mc^2. Due to the innumerable amount of reactions taking place every second and the Sun’s large mass, nuclear fusion will provide enough energy for the Sun to shine for 10 billion years. So don’t worry about the Sun running out of power anytime soon.
The atmosphere is split into four different layers: the troposphere, the stratosphere, the thermosphere, and the exosphere. The troposphere is the lowest layer and is where greenhouse gasses absorb the infrared light and where storms occur. The stratosphere absorbs solar ultraviolet light by ozone, Earth is the only planet to have this layer. The thermosphere absorbs x-rays and makes radio communication possible. The exosphere is the fuzzy boundary between the atmosphere and space.
Just as all things have a beginning, all things have an end. Unfortunately this applies to our Sun as well. As a kid, I used to think that the Sun was basically just like a lamp light in the sky. When a lamp runs out of batteries, all you have to do to make it shine again is replace its light bulb. This is not the case with the Sun. Our Sun has been burning brightly for about 5 billion years (that’s an extremely long time!). The Sun is expected to burn for a total of 10 billion years, so it’s about halfway through it’s life-cycle. The looming question is: “what will happen to the Sun and our solar system when the Sun dies”?
Originally, scientists believed that it would turn into a bubble of cosmic dust and gas. In order for that to happen though, the sun would have to be a bit more massive than it currently is. In about 5 billion years when the Sun uses up all of its nuclear fuel, it will turn into a red giant. Both Mercury and Venus will be swallowed and the Earth will be burnt to a crisp. It’s core will begin to shrink and then eject its outer layers to engulf everything to the outer layer of Mars. Fortunately, or unfortunately, we won’t be around to see all of this happen. Humans are actually only expected to live for about 1 billion more years because the Sun is gradually increasing in brightness. The Earth’s surface will eventually become so hot that it will be impossible for water to form. But until that time comes, humans are on the search for a new home in order to keep humanity alive!
You can find more information about what the end of our Sun’s life looks like here. If you need some more convincing from some professionals, here is a website where some scientists talk about the Sun’s end.
The Trappist 1 system is a collection of seven rocky worlds that orbit an ultra cool dwarf star which was named 2MASS J23062928-0502285 at the time of its discovery because of the telescope used. All of the worlds in Trappist 1 are Earth-like meaning it contains the same elements like iron, oxygen, magnesium, etc; however, it is assumed they are in different ratios because the masses of all seven are lighter than the mass of Earth. They are all likely to have liquid water, and the most Earth-like planet of this system is Trappist 1-E (the fourth planet from the central star).
My interest in this system mainly stems from my love for astrobiology – the study of life on other planets – because of the sheer amounts of evidence collected suggesting 1-E is like Earth. Trappist 1E lies in the habitable zone of its central star just like Earth does. Coupled with the fact that there’s liquid water, this means there is a possibility for life to survive with the right temperatures from the stars and evolve like microorganisms did millions of years ago on Earth.
This system was discovered rather recently, and it’s only around 40 light years away; so, it will be super interesting to see what we discover in the ever evolving realm of science!!
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There are places where amazing things happen. More specifically, there are points in space within which gravity pulls so tightly and on such a small area of surface that the space collapses in on itself, The space bends so much that even light, the fastest thing known to exist, can not escape its grasp. These awesome occurrences are named “Black Holes”, and they are incredibles feats of mother nature’s power. Black holes can typically form when a lot of matter is squeezed in very tight places like when a star dies, for example. They can be big or small, but they are usually formed by bigger stars than the Sun. Light can not escape the black holes, so they are observed by looking at the mass in space and the places that are dark and have a lot of mass are black holes.
For many students growing up in Chicago, the Adler Planetarium is staple in the field trip rotation. Having attended multiple times a year for years and even going to their summer camp at one point, Adler Planetarium is something I am proud of as a Chicago native. As of March 2023, Adler has 12 different exhibits, but my favourite activity at Adler is linked in the video above or here.
The best way to explain the Planetarium Sky Show is like going to the movies to watch the sky. The theatre itself is in the shape of a dome and the seats recline emulating the way our ancestors would lie on the ground and observe. In a city like Chicago, observing seems nearly impossible but during the Sky Show I felt like I had taken a plane to lands far away from light pollution and unclear Skys. Having done some observing in rural Tanzania, I draw the comparison that experiences like these make people understand why the universe is worth discovering.
If you do find yourself in Chicago with time to visit Adler, be sure to buy tickets ahead of time! Everyone loves a good sky show.
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As discussed in the textbook, most comets are not visible within Earth because they rarely pass through the inner solar system. Alternatively, they orbit the Sun within the Kuiper belt and Oort Cloud. Previously my knowledge of comet’s was bound to Halley’s comet, which is arguably one of the most famous of the comets to have been observed, and seen return. Within the discussion of Haley’s comet, people also are made aware that due to the comet’s ~75 year orbital period, its next predicted return date is in July of 2061. Luckily for us we do not have to wait 38 years to see a beautiful comet in our sky.
Photo of Astronomers’ Tracking of the comet’s current position in space found here
According to Nield (2023), C/2023 A3 (Tsuchinshan-ATLAS) a comet within our Solar System is approaching our view and will be visible in October 2024. The interesting thing I found about this comet is its brightness. As of now astronomers have predicted Tsuchinshan-ATLAS’ brightness magnitude to be about 0.7 and as it passes closest to Earth it will be close to -0.2. Thus, when Tsuchinshan-ATLAS is visible, it will be one of the brightest objects in our night sky.
To say this will be a once in a life time experience is absolutely correct. According to Guenot (2023), the last time this comet passed by Earth was approximately 80,000 years ago. Thus, after 2024, it will not be visible again for well after even out great-grandkids’ lifetimes. Be sure to mark your calendars, in advance so you don’t miss out!
We know that Earth is the only planet in the solar system currently capable of housing liquid water. The other planets are too low pressure or too hot for water to exist as it does on Earth. However, other bodies in the solar system do have solid water, also known as ice! The moon and Mars both contain ice at their poles. The question is, how did it get there?
Currently there is no complete consensus of how water ended up on Earth or on other planets. The leading theory is that asteroids formed in the solar system and contained ice. These asteroids were massive and had diameters on the scale hundreds of kilometers. Such asteroids are still seen today in between Mars and Jupiter. The asteroids once contained ice, but due to radioactive decay, the ice has melted into water and combined with minerals in the asteroids to form clays. Once the asteroids impacted with the planets of the solar system, the resulting energy would scatter the elements in the asteroid and vaporize the clays back into water. It’s even possible that the asteroids contained the base elements required for organic compounds.
Interestingly, our water is being lost to space continuously. The water vapor high up in the atmosphere is being struck with photons, which separates the hydrogen atoms. Sometimes, the atoms can be given enough energy to escape Earth’s gravitational pull, becoming lost forever in space. We can use this fact to estimate when water arrived on Earth, and how much water we used to have.
A neat Youtube Video on what terraforming Mars could look like
Is it possible to give Mars a livable atmosphere? In theory, yes! However, it would be infeasible to do it in our lifetimes. Or within the next couple hundred years. This video from Kurzgesagt (fantastic channel, by the way) details how we might be able to give Mars an atmosphere and biosphere using our current understanding of the composition of Mars. To summarize the already heavily summarized video, by using incredibly powerful lasers, we can melt millions of tons of rock on the surface of Mars in order to free the gasses needed to form an ideal atmosphere. This process alone would take dozens of years of constant laser -ing, and that’s not accounting for the time it would take to develop, build, and deploy the lasers themselves. Assuming we are able to fill Mars with the oxygen, nitrogen, and carbon dioxide it needs to sustain life, we would need to implement the biosphere itself. According to the video, it could take centuries to maybe even a thousand years to perfect a stable biosphere. Finally, we would need to protect Mars from high energy solar radiation. To do so, we would need to generate a small magnetosphere around the planet, which the video goes into a little detail about. Finally, after all of that, we could consider Mars to be terraformed and perfectly habitable.
All of the concepts in the video are far fetched based on our current technological capabilities. However, everything stated in the video is based on physics. It is possible for lasers to melt rock and generate an atmosphere, and it is possible for us to transport nitrogen from other planets. However, to suggest that we are even close to being able to execute these plans is a little silly. In the meantime, it is pretty cool to see how we might one day terraform other planets.
Voyager 1is the farthest human-made object from Earth (Space.com). Voyager 1 is a space probe, launched in 1977 with the mission to explore the outer planets of the Solar System. Voyager 2, its twin probe, was actually launched first, with a slower, more meandering trajectory past Jupiter, Saturn, Uranus, and Neptune. Voyager 1 soon overtook 2, since its trajectory focused on Jupiter and Saturn, allowing it to take a more optimal gravitational path to those planets.
Voyager 1 is currently 14.6 billion miles from Earth, which is equivalent to about 157 Earth-Sun distances, or 4 Pluto-Sun distances. Voyager 1 has crossed the heliopause, which means that it has exited the heliosphere–the 100 AU radius bubble of space around the Sun that constitutes the magnetosphere and outermost atmospheric layer of the Sun. This space is the domain of solar wind, and outside of the heliosphere, solar plasma is replaced by the interstellar plasma that permeates the galaxy. Thus, Voyager 1 is considered to have entered interstellar space, even though it is still far from reaching the Oort Cloud–the predicted spherical region of icy objects 2,000-100,000 AU from the Sun. Even though Voyager 1 is speeding through interstellar space at 38,000 mph (17 km/s), it will not encounter the Oort Cloud for 300 years, or exit it for 30,000 years (NASA). In 40,000 years, Voyager 1 will reach another star–drifting within the 1.6 light-year vicinity of Gliese 445 within the constellation Camelopardalis. At this time, Gliese 445 will be tied for the closest star to the Sun (Wikipedia).
The possibility of a near encounter with another star system calls to attention another important feature of the Voyager probes: the Voyager Golden Records–two phonograph records containing the sights and sounds of Earth, intended to communicate a frozen-in-time story of Earth to potential extraterrestrials. Engraved on the cover of the records are instructions for playing the records, a description of the location of the solar system with respect to 14 pulsars, and a drawing indicating that the time interval associated with hydrogen’s transition between two states should be used as a fundamental time scale (NASA). A source of Uranium-238 electroplated onto the cover is intended to provide a way to calculate how old the record is using radioactive dating.
The Golden Record, next to recreations of the engravings on the cover. Source
I am torn regarding my opinion of the decision to include the Golden Records on the Voyager missions. On one hand, it is extraordinarily romantic–the records include natural sounds of earth, like of the ocean, wind, thunder, and animals; as well as human audio sources, like greetings in 55 languages, laughter, and music from around the world. There are images of scientific interest, showing our understanding of math, physics, astronomy, and biology. There are images of Earth, showing food, architecture, and people of all ages and sexes in all sorts of scenarios. The records are a sort of love letter to Earth, allowing our society to live on in memory, somewhere in the universe, even if we are no longer around to know about it.
On the other hand, I have concerns about the implications of our exact address in the galaxy being broadcast into the ether–what if aliens find our records, decode our messages, and aren’t altogether very nice? If we are still around in 40,000 years, or longer, considering that the Golden Records are expected to still be at least partially intact in 5 billion years (Space.com), we might be in some trouble if this extraterrestrial civilization rivals or exceeds our technological advancement. The fact that the records do not include any images that suggest that Earth has any kind of defense mechanisms might contribute to this problem–extraterrestrials might assume that we are easy targets (Retrospect Journal), but on the other hand, might recognize that the lack of visible defense mechanisms does not imply that they don’t exist. Perhaps they will deem us too far away, or will conclude that we probably haven’t survived the past 40,000 years anyway, so it’s not altogether worth it to try to come kill us.
All in all, I’m not sure whether or not I think Voyager 1 and its Golden Record will pave the way for humanity’s doom, but it’s comforting to know that the beauty of Earth will live on, long beyond the start of its era of uninhabitability for humans (Science). What do you think about this dilemma?
