Terrestrial planets’ atmospheres, including those of Venus, Earth, and Mars, are crucial to their general behavior and possible habitability. Many elements, including the planet’s distance from the sun, the makeup of its surface, and the presence of geological activity, all impact these atmospheres. The atmospheres of terrestrial worlds display a startling variation in behavior and characteristics despite having identical chemical compositions.
For instance, Venus has a very dense and hostile atmosphere, with surface pressures 90 times higher than Earth’s. Carbon dioxide dominates the atmosphere, with minor amounts of nitrogen and sulfuric acid. Venus is the hottest planet in our solar system because of a greenhouse effect caused by the planet’s dense clouds, which reflect a large portion of the sun’s energy back into space. Despite Venus’ hostile environment, researchers are still looking for hints about the planet’s geological past and possibilities for life.
Yet, compared to Earth and Venus, Mars has a much thinner atmosphere that ismainlyy made of carbon dioxide with minute amounts of nitrogen and argon. Mars has a surface temperature of about -80 degrees Fahrenheit.
Earth’s atmosphere is by far the most habitable since it supports us ‘humans’. With traces of carbon dioxide, water vapor, and other gases, nitrogen and oxygen make up the majority of the atmosphere on Earth. The atmosphere is essential for maintaining a stable climate, controlling the planet’s temperature, shielding it from dangerous solar radiation, and supporting weather patterns and ocean currents.
In conclusion, the atmospheres of terrestrial worlds are incredibly diverse and fascinating, providing critical insights into the nature of these planets.
Titius Bode’s law is a fascinating concept in astronomy that has been intriguing scientists for centuries. This law is a mathematical relationship between the distances of the planets in our solar system from the Sun. It was first formulated in the 18th century by Johann Daniel Titius and later popularized by Johann Elert Bode.
Portrait of Johann Daniel Titius. Source: WikipediaPortrait of Johann Elert Bode. Source: Wikipedia
According to Titius Bode’s law, there is a pattern in the distances of the planets from the Sun. This pattern is represented by a simple mathematical formula that can be used to predict the distance of a planet from the Sun based on its position in the solar system.
First, let’s take a look at the table below, which shows the distances of the planets from the Sun in astronomical units (AU), as predicted by Titius Bode’s law:
Planets
Distance (AU)
Mercury
0.4
Venus
0.7
Earth
1.0
Mars
1.6
Ceres
2.8
Jupiter
5.2
Saturn
10.0
Uranus
19.6
Neptune
38.8
As you can see, the distances of the planets follow a clear pattern: each planet is approximately twice as far from the Sun as the previous planet. This pattern continues until Neptune, which is located much farther from the Sun than predicted by the law.
Interestingly, Titius Bode’s law also predicted the existence of a planet between Mars and Jupiter, which was later discovered and named Ceres. This discovery was significant because it provided evidence for the existence of a previously unknown region of the solar system, now known as the asteroid belt.
Despite its accuracy in predicting the distances of most of the planets, there is still some debate among astronomers about the significance of Titius Bode’s law. Some argue that it is simply a coincidence, while others suggest that it may be related to the formation of our solar system.
One hypothesis is that the law reflects the distribution of matter in the early solar system. According to this theory, the matter in the solar system was distributed in a series of rings, with planets forming in regions where the density of matter was highest. Titius Bode’s law may reflect this distribution of matter, with each planet forming in a ring that was approximately twice as far from the Sun as the previous ring.
Titius Bode’s law has been using to search for new planets beyond our solar system. By applying the same mathematical formula to other star systems, astronomers can estimate the likely distances of any planets that might be orbiting those stars. This information can then be used to guide the search for exoplanets, or planets located outside of our solar system.
The international space station is a collaboration that unites humanity to pursue the largest frontier, space. The ISS is the largest and most equipped space station humanity has ever had in space and provides opportunities to research exploration of space and how to help people back on earth. The ISS orbits the earth 386 kilometers above the Earth and has been home for a rotating crew of astronauts. These crews stay on orbit for six months at a time and learn about how living in space affects the human body physically and psychologically. Solar panels on the station are larger than the wingspan of a jet plane which being in constant orbit s able to harness energy from the sun and provide electrical power to all parts of the station. 16 different countries are involved with the ISS and each played a role in building the 15000 cubic feet of habitable space. The ISS has been indispensable in providing information for the future of humanity’s venture into space and provides a deeper understanding for how we can survive in the universe.
Among all of Earth’s unique aspects and characteristics, the presence of water may be the most significant. Water is necessary to life as we know it; from humans ourselves down to microscopic organisms, all living things need water to survive. It is no wonder, then, that life in the Solar System is exclusive to Earth; when we look at the other planets, we see barren wastes or gas clouds instead of water.
Though life in the Solar System is exclusive to Earth, water is not uniquely ours. Mars notably has ice caps and is sometimes theorized to have once had oceans of liquid water. The more notable example, however, is Jupiter’s moon of Europa. Europa’s surface is almost entirely ice, but it is widely accepted that beneath that ice is an immense ocean of liquid water, greater even that Earth’s stores.
Of course, water alone is far from sufficient for life to form. However, it is not out of the question that microscopic life could exist on Europa. The moon is exposed to Jupiter’s radiation, which could present the necessary conditions for life to form in its oceans. The presence of life on Europa has not been confirmed in any way, but it is possible.
Though we often think of ourselves as alone in the Solar System and even the galaxy, it is critical to recognize that the conditions for life, though specific, can be met in a multitude of ways. Europa provides an example of potential life, as bacteria or other microorganisms may well exist in its oceans.
A diagram of the Solar System showing the planet Vulcan
While the five planets visible to the naked eye have been known for almost all of astronomy’s history, it was not until the discovery of Uranus in 1781 by Sir William Herschel that astronomers began searching for other planets in our Solar System. After Neptune was discovered in 1846, astronomers began turning their telescopes towards the sun in search of another planet, seeking to explain Mercury’s strange behavior. It had been known for some time that Mercury’s orbit precessed slowly over time, and in 1859 French mathematician Urbain Le Verrier predicted that there must be another small planet even closer to the Sun whose gravity caused the odd motion. While many astronomers searched for Vulcan over the coming years, no truly confirmed sightings were ever made (as it does not exist) and Mercury’s orbital precession was eventually explained as a relativistic effect of the Sun.
Nearly every component of our body and the planet we call home was created inside stars. Heavy atoms like carbon, nitrogen, and oxygen are produced from lighter elements like hydrogen and helium through the nuclear fusion process that takes place in stars. These substances are released into space when a star undergoes a supernova explosion after its life as seen in this image. The immense clouds of gas and dust between stars are known as the interstellar medium, including the fragments left over from these explosions. Eventually, gravity causes these clouds to collapse, forming new stars and planets. And because these clouds contain elements like carbon and nitrogen, which are essential for life as we know it, the planets that form around these stars can also support life.
So, in a genuine sense, we are made of the same material that stars are made of. The carbon in our DNA, the calcium in our bones, and the iron in our blood were all forged in the fiery hearts of stars that exploded billions of years ago. It’s a humbling thought but also a reminder of our connection to the universe around us. We are not separate from the cosmos but rather a part of it. And that’s something worth celebrating.
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With our totally unrestricted guidelines on Blog 4, I would like to make a bit of a deviation from the content of our course and discuss time dilation and the theory of relativity!
In the movie Interstellar, a planet is so close to a black hole that the immense force of gravity of the black hole causes one hour of time on the planet to constitute seven years on Earth. Source
When I first learned about time dilation, which refers to the difference in elapsed time as measured by different clocks due to different relative velocities of the clocks or different gravities acting on the clocks, I couldn’t wrap my brain around it. Time dilation hinges on the idea that time is not a universal constant, rather, the speed of light is constant. This is extremely difficult to understand on Earth–we have no firsthand experience with anything other than the perceived constant, slow march of time steadily ahead. I could not understand how the speed of a photon exiting a flashlight held by a person at rest could possibly be the same as for a photon exiting a flashlight held by a person riding a bike–obviously speeds are additive!
In fact they are not–not where relativistic speeds are concerned. The speed of light is a universal speed limit, no object can move faster. What finally helped me understand this was a YouTube video, which explains a couple of Albert Einstein‘s thought experiments. I would like to explain it here!
While riding the train home from his job as a clerk, Einstein looked at a clocktower behind him, receding into the distance. He could see the second hand ticking as time passed and he moved further away. He thought–what if this train was moving at the speed of light? The clock hand would appear to be still–photons must travel from an object to your eye for you to be able to see it, and if you are moving away from the photon as fast as it is moving toward you, it will never reach your eye. The clock hand would appear frozen in time, even though the clock would still appear to tick away from the perspective of someone standing next to the clock. (Note: technically time can’t be “frozen”–since no object can actually travel at the speed of light, we must settle for very close to the speed of light, so the clock hand will still move very slowly.)
How can this be possible? Isaac Newton‘s laws of motion state that velocities are never absolute, but must be described in relation to something else. For example, a car may travel 60 mph with respect to a person standing on the side of the road, but it will appear to travel 40 mph with respect to a person in a car traveling 20 mph in the same direction. It will appear to travel 80 mph with respect to a person in a car traveling 20 mph in the opposite direction. However, James Clark Maxwell found experimentally that the speed of light is fixed, regardless of who is observing it.
Newton’s laws describe that velocity is relative to some observer. Source
These two ideas are, on the surface, contradicting. How can the speed of light be constant, if speeds must be measured relative to some other object?
Einstein’s solution was to make a small adjustment to Newton’s laws, while still upholding the constancy of the speed of light. He proposed that time must slow down for objects traveling at great speeds, in order to keep the speed of light constant. This was called time dilation–time does not move steadily forward, but can stretch and contract with varying velocity of motion. It is important to note that Newton’s laws still work for non-relativistic situations, which is why we haven’t completely thrown them out!
To accommodate time dilation, Einstein further developed the concept of spacetime–the idea that time and space are not separate entities, but are inextricably intertwined into one entity. Gravity causes distortions of spacetime–this can be imagined as 3D dips in a 2D “fabric” of spacetime, meant to represent the actual 4D spacetime. Smaller objects orbit around larger ones since they are caught in the curved dip of spacetime around the larger object.
We know that the force of gravity on an object increases with decreasing distance from another object–most noticeably if a small object is approaching a larger one. This difference in forces represents a difference in accelerations–imagine a person falling faster as they approach the Earth. Now, consider what we just learned–that the faster you move through space, the slower you move through time. A clock in high-Earth orbit around will tick faster than the clock on your desk, since the gravitational forces, and thus accelerations, on the two are different.
We can look at another thought experiment to understand why this is so. Imagine a person falling from high-Earth orbit down to the ground, carrying a photon clock–a theoretical clock for which it takes one second for a photon to bounce between two reflective surfaces. Another observer stands on the ground. What will they observe as the person falls from space?
The falling person will see the light from their own clock traveling in a straight line back and forth, much like when you throw a ball upward and catch it while traveling in a car–it doesn’t move behind your head. On the other hand, the observer will see the light traveling in diagonal lines, much like if an observer outside the car were to see you throwing the ball up and down. The net movement of the ball, or the photon, would appear to be a zig-zag.
What does this mean for our clock? Light is observed by the person on Earth to travel a greater distance–the diagonal lines are longer than the straight ones. Since the speed of light is constant, and the confines of the start and the end of the event are the same, this must mean that time has gotten shorter. The duration of a second is not constant–it is proportional to the velocity of the object in motion.
In order to accommodate light traveling a longer distance at the same speed, the time between two set start and end events must change. Source
This has been experimentally proven–time records of clocks on spaceships that have spent a decent amount of time in space are different from time records of the same “event” as measured by clocks on Earth. Time passes at different speeds, and thus the total amount of time elapsed is different.
We have explored here time dilation and the theory of relativity–the idea that if the speed of light is constant, which has been repeatedly proven to be true, then time must not be constant in order to compensate for light traveling different distances based on motion and gravity. Thank you all for sticking around, and if you never understood Interstellar, I hope this explanation helps!
Dark Matter is a fascinating topic, yet we know so little about it. Regardless, a good amount of evidence exists that indicates dark matter is real. One pertains to the flatness of rotation curves for spiral galaxies at extended distances. The graph does not drop off, but rather, continues in (essentially) a flat rotation curve, indicating the presence of much more mass and therefore large amounts of dark matter.
We can also find more evidence for dark matter by measuring the velocities of galaxies within a galaxy cluster from their Doppler Shifts. The mass we calculate is roughly 50 times greater than the mass of all the stars in that galaxy cluster! The 3rd line of evidence also has to do with galaxy clusters. Clusters contain great amounts of X-Ray emitting hot gas (since they have a strong gravitational ability to hoard large amounts of interstellar gas). The temperature of this hot gas (which we infer from particle motions) reveals the mass of the galaxy cluster. Estimates conclude that ~85% of galaxy clusters are Dark Matter, with the rest being gas and stars. We can use Gravitational Lensing (the warping of light rays by gravity over large distances) to discern a cluster’s mass.
So what options are astronomers left with regarding dark matter? Well, either dark matter really does exist, and we are seeing the evidence of its gravitational attraction, or something is horribly wrong with our understanding of gravity, causing us to erroneously surmise that dark matter exists. However, because gravity is so well tested, most astronomers agree that dark matter is real.
Based on Einstein’s theory of relativity, black holes have a theoretical opposite know as “white holes”. Rather than it being impossible for matter to exit (as is the case with black holes), it would be impossible for matter to enter a white hole. Physically, it would look very similar to a black hole: the only difference would be matter being ejected from the horizon. A white hole is both a black hole’s twin and its opposite.
Black holes exist largely on the edge of our understanding of physics, and the idea of white holes can be used to explain some of the inconsistencies we see. For example, black holes leak energy, implying that one day they may disappear entirely. If that occurs, we have no theoretical explanation for what happens to the matter that has entered the black hole that doesn’t violate the laws of physics. One explanation would be that a white hole forms upon the death of a black hole.
Illustration of black and white holes as opposite. Sourced from this article.
Unfortunately, no white hole has ever been observed, and there are still many practical barriers to them even existing. Black holes are formed by a star collapsing in on itself, but the opposite–a star forming from an event horizon–violates laws of entropy. Furthermore, if a white hole was constantly ejecting matter into its orbit, the collisions would eventually cause a collapse back into a black hole. So, while the idea of a white hole is interesting and would answer unanswered questions about black holes, odds are low they really exist, or if they do, don’t stay alive for long.
Information from this blog is sourced from this article.
Climate Change is one of the most important issues that has already affected our lives and one that threatens our future. To get an understanding we need to look back in history to when human’s began to cause a shift in the climate. In the 1800s, humans began the industrial revolution thus having to burn tons of coal, natural gases, and oil in order to generate electricity and power our various machines. Due to us burning these tons of fossil fuels since than we have added extreme amounts of CO2 and other greenhouse gases into the atmosphere. These greenhouse gases stop heat from escaping the earth into space, thus with the amount we have generated over the last few centuries we have been trapping too much heat than what is natural for the world. According to data, the planet is already 1.8 degrees Fahrenheit hotter than it was in the 1880s and this will only continue to rise as we burn more and more. For the future if we do not keep this in check there is evidence that sea levels will rise, flooding could occur in large cities, hurricanes will become stronger, and many more. We still have time to prevent this and everyone has the ability to do their part to secure our planet’s future. People who deny climate change exist are truly ignorant and will continue to further this problem, which is why its crucial to educate the next generations so that they are equipped to tackle the challenges that lie ahead.
