Earth’s Atmosphere and Life

Posted on March 21, 2022 by solarelizabeth
The Greenhouse Effect!

Earth’s atmosphere is conducive to life in a way other terrestrial worlds’ atmospheres are not. 

This is because of the greenhouse effect, which keeps Earth warm and allows water to exist in its liquid form. Other planets such as Mercury which do not have an atmosphere or the greenhouse effect are extremely hot during the day and frigid at night. Earth, however, has a much more regulated temperature because of its atmospheric composition, which is conducive to the greenhouse effect. 

The sun gives off energy that warms the Earth, mostly in the form of visible light. This energy is absorbed by Earth’s surface and some is reflected back into space as infrared light (planets are not hot enough to emit visible light). Greenhouse gasses such as water vapor, methane, and carbon dioxide absorb and reemit these infrared photons. Emitted photons are absorbed by other greenhouse gas molecules and then reemitted.The escape of infrared light into space is slowed and this passing around of the molecules heats the atmosphere. It’s interesting to consider that though Earth’s atmosphere is made mostly of nitrogen and oxygen, the small proportion of greenhouse gases still has a meaningful impact on temperature regulation. On the other hand, Venus has a much stronger greenhouse effect than Earth because it has a much larger portion of carbon dioxide, a greenhouse gas, in its atmosphere. Venus is scorching hot all of the time because of its greenhouse effect. Earth is not as hot because its atmosphere has a smaller composition of greenhouse gases.

Do you think the daytime and nighttime temperatures would be more different for a planet with a greenhouse effect or without a greenhouse effect?

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Blog 3: Climate Change

Posted on March 21, 2022 by camsto42
NPR Carbon Footprint

Astronomy has been around for many many years, as we have learned in class. Astronomy used to be a hobby for the wealthy, now it is an occupation for the smartest to learn about the universe we are in. One major facet that astronomers have observed and questioned is climate change. Recently, it has become evident that the new telescopes we use are contributing to the climate problems. This is a huge problem because as we search for answers to the serious problem we have in our world, we make the problem exponentially worse. The most expensive observatories, such as the one that houses the James Webb telescope, are the ones that cause the most emission, and these observatories are those that gather the most data. This is an example of a compounding problem, and many different solutions are being explored. Two solutions that are presenting themselves are the use of solar power, and the use of greener energy. Both of these are better options, as the cause less emission, and observatories around the world are slowly going to adopt these policies.

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The moon’s origin

Posted on March 21, 2022 by joubertklopper

Earth’s moon is unique for several reasons. Earth’s moon relevant to its planet’s size, Earth is the largest in our solar system and that fact has drawn my curiosity to the subject of the moon’s origins and what makes it so unique.

It is speculated that the moon originated when another terrestrial planet, Theia crashed into earth. This theory is called the giant-impact theory. The giant-impact theory hypothesizes that Theia was about the size of Mars and collided with earth and caused a huge impact. The theory furthermore says that Theia was completely destroyed while Earth obviously survived. The impact made Earth spin so fast that the days shortly after impact were around 5 hours. Most of Thea was completely destroyed; however some of the debris of the collision remained and orbited earth and through that the Moon was formed.

The giant impact which formed the Moon

This theory is supported by the fact that the rocks collected from the moon from the Apollo missions were very similar to the rocks that could be found on earth. What was different however, was that the Moon’s rocks were much drier than the rocks from Earth. A giant energy occurrence must have happened on the Moon with the Moon heating up to extraordinary levels causing the rocks to completely dry out. The giant-impact theory accurately explains this.

The YouTube video https://www.youtube.com/watch?v=o2lRpiediP8 does a great job explaining the collusion and the visuals are super interesting and fun to watch!

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Earth and Venus: Zach and Cody?

Posted on March 21, 2022 by joubertklopper

Scientists argue that Venus is earth’s astronomical twin for a number on reasons. Like Zach and Cody from the Disney Channel sitcom, The Suite Life of Zach and Cody their physical similarities and dependance on each other cannot be overlooked.

Looking at Earth and Venus’ similarities, the similar diameter comes to mind. The diameter of Venus is 12,103.6 km. That’s only 95% of the Earth’s diameter of 12,756.2 km. If we were to place the two twins next to each other we would struggle to distinguish between the sizes of both terrestrial worlds. Second, because of their similar size, their internal content are also pretty similar. Both have a similar sized core made up of mostly metal, their crust is also a similar size and is mostly mad out of rock. Needless to say due to their similar, large size heat escapes at a slower pace keeping both Earth and Venus’ interiors warm and therefore has a thin lithosphere.

Earth and its twin

Venus might be a twin in a lot of aspects, but in some Venus is vastly different than Earth. Venus’ temperature is around 93 times that of the temperature experienced on Earth. Due to these high temperatures Venus is almost completely dry. The high temperatures, lack of water combined with the lack of oxygen on Venus explains why we have yet to discover any signs of life on Earth’s twin planet.

Venus looking at Earth having moderate temperatures, water and oxygen like…

Looking at what was said from above, the biggest similarity between Earth and Venus is their composition and the biggest difference is Earth’s environment encourages life while Venus’ doesn’t.

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The Sun’s Nuclear Fusion

Posted on March 20, 2022 by solarelizabeth
The chemistry behind nuclear fusion.

The Sun has been producing a huge amount of energy for over 4 billion years through nuclear fusion. Nuclear fusion is the process by which the Sun converts mass to energy. Albert Einstein’s equation, E=mc^2, reveals that a little bit of mass has a huge amount of potential energy which indicates why the sun has been able to shine for so long. In fusion, nuclei smash into each other at high speeds and fuse together to form nuclei with higher atomic weights. In this process, some of the mass is converted into energy. 

When the Sun undergoes nuclear fusion, four hydrogen nuclei fuse together to form a Helium nucleus. The Sun’s nuclear fusion process is called the proton-proton chain. This is because two Hydrogen nuclei, which are each a single proton, fuse to form a deuterium nucleus, which is one proton and one neutron. Then, the deuterium nucleus fuses with another Hydrogen proton to form Helium-3. The Helium-3 nucleus fuses with another Helium-3 nucleus to form a Helium nucleus with two protons and two neutrons. The two extra protons are released. In this process, a tiny amount of mass disappears, but it is transformed into a huge amount of energy. The energy is released in the form of gamma rays, neutrinos, and positrons. 


When the sun was forming, the cloud that would become the sun contracted under gravity and became hotter and more dense, setting the stage for nuclear fusion. Nuclear fusion occurs in the Sun’s core because it is the hottest and most dense area, with the core temperature being about 15.6 million K. High temperature and density are required because like charges repel each other, so Hydrogen nuclei would not fuse together to form Helium nuclei otherwise. The point is, the Sun generates its energy because it is massive enough to sustain a hot and dense core, which overcomes repulsion of Hydrogen atoms of the same charge, smashing them together to form Helium. This results in some mass being converted to energy, which we know is an enormous amount because of Einstein’s E=mc^2.

Thanks for reading!! Let me know what fusion processes you think would happen in more massive, hotter stars!

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Blog#4 Dark Energy and Dark Matter

Posted on March 20, 2022 by Irene

Dark Energy and Dark Matter sound both exotic (and yes they absolutely are) but they have very different meanings and opposite effects: One expands our universe while one creates more gravity.

High-z Supernova Search Team was founded in 1994 and in 1998 they found that one investigated supernova is fainter than Hubble’s law predicted. This mismatch could only result from either a wrong prediction or the actual distance of the supernova becomes more distant. After careful research, they claimed that the supernova is accelerating away from us and the Universe is actually expanding and won the 2011 Nobel Prize. What causes the anti-gravity effect is called Dark Energy. Dark Energy bubble out of the vacuum of space, creates a pressure that forces space to expand to an ever-increasing rate, and makes galaxies move faster and faster.

Nonetheless, it is quintessential to know that what is expanding is space-time. Galaxies are like raisins in dough and the dough itself is expanding. 

Artistic Illustration of an Accelerating Universe.

Dark matter was proposed by Fritz Zwicky who was a professor at CalTech in the 1930s. In 1933, he found that galaxies in Coma Cluster moved faster than expected. Therefore, there must have lots of mass we cannot see: 50 times more than the mass we can see. That is to say, 98% of the mass in our Universe is dark. Later the number is reduced to 97%.

Fritz Zwicky

The concept of Dark Matter was further testified by Vera Rabin in 1962. She calculated and graphed stellar curves of the velocities of stars. She found that the velocities didn’t decrease as expected for Keplerian orbits, which means there must be an invisible mass. 

Vera Rabin

Nonetheless, human beings still barely know about dark matter. There is not enough helium in the Universe to make that much mass and there is no evidence for normal stuff to be dark, yet the gravitational lensing proved it existent. We have hypotheses for Dark Matter including Machos (Massive Compact Halo Objects), Axions (cold candidate that made in Big Bang), and WIMPS (weakly interacting massive particles). However, nothing was found. So, are dark energy and dark matter the ether of the 20th and 21st centuries? 

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Blog#3 Radioactive Decay

Posted on March 20, 2022 by Irene

Our world is composed of elements all of which are made of protons, neutrons, and electrons. Protons are positively charged while electrons are negatively charged. Unstable (i.e., radioactive) atomic nuclei can become more stable after the emission of particles and energy, a process called radioactive decay. These emitted particles or energy (the latter emitted as electromagnetic waves) are collectively called radiation.

Illustration of Radioactive Decay. Cr. Wikipedia

There are three types of radioactive decay: α decay, β decay, and γ decay

In the alpha-decay process, a nucleus releases an alpha particle (a helium nucleus formed by two neutrons and two protons) and transforms into a new nucleus with a reduced mass of 4 and a reduced nuclear charge of 2. Alpha radiation releases discrete energy and can be almost completely absorbed by a layer of air several centimeters thick.

In the Beta-decay process, a nucleus releases a beta particle (electron or positron). It releases continuous energy and can be absorbed by a few millimeter aluminum layers. 

Gamma radiation is usually produced along with other forms of radiation, such as alpha radiation and beta radiation. When an atomic nucleus undergoes alpha decay or beta decay, the resulting new nucleus is sometimes in an excited state, at which time the new nucleus leaps to a lower energy level and simultaneously releases gamma particles. This is gamma radiation. It releases discrete energy and has an infinite effective range. Nonetheless, it can be absorbed by about a 10-centimeter lead board. 

During the decay of a radionuclide, the number of nuclei of the nuclide gradually decreases. The number of nuclei that will decay per second is proportional to the number of nuclei at present that has not yet decayed. Therefore, there is an exponential decay equation. The time it takes to decay to only half its original mass is called the half-life of the nuclide. Each radionuclide has a specific half-life, ranging from a few microseconds to several million years. We can use radioactive dating to measure how old an object is.

Exponential Decay and Half-Life. Cr. Wikipedia
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Halley’s Comet

Posted on March 20, 2022 by jesszhang782
Halley’s Comet was the first comet understood to be a periodic comet, or a comet that can pass through the solar system multiple times. The English astronomer Edmund Halley (1656-1742) noticed that the previously recorded orbits of three comets were very similar and suggested that it was actually the same comet returning it its orbit. […]
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Solar Sailing Through The Sea of Space

Posted on March 20, 2022 by josephmaquino9
Figure 1: The Japanese IKAROS solar-powered spacecraft.

As an imaginative mind might ask: can we use the Sun’s light to propel a spacecraft through space? Surprisingly, this avenue of spacecraft propulsion has, and is being, explored. Figure 1 displays the Japanese IKAROS satellite that was deployed on May 21, 2010. The spacecraft was equipped with a 14 m x 14 m solar sail membrane that served as the primary attitude control. Interestinly, the satellite utilized the flow of electricity through the liquid crystal panels in the membrane to steer it in different directions. So, why does this concept work?

Just as it applies in rocketry, conservation of momentum is the driving concept behind a spacecraft with a solar sail. Light is comprised of photons. Although these particles are massless, they have momentum as they travel through space. Thus, when photons reflect off of the sail, momentum is transferred into the spacecraft. The exciting thing about solar sailing through space is that space is a vacuum. This means that there is no drag acting on the spacecraft, and each reflection of a photon increases the vehicle’s velocity. Additionally, the Sun’s light is not going to be extinguished in the very near future, so the solar sail will have a continuous input of light.

Now, you may be asking, “14 m x 14 m is a very large sail, isn’t it?” You would be correct. To keep the mass of the vehicle down, solar sails tend to have a thickness on the magnitude of microns (or 10^-6 m). The IKAROS satellite’s solar sail membrane had a thickness of only 7.5 microns, causing the spacecraft to have a total weight of approximately 310 kg. Since there is continuous light striking the solar sail, the only real negative impact of more mass in space is that it would take the vehicle longer to accelerate (as conservation of momentum considers mass). The main concern with mass is that the spacecraft has to be transported out of the Earth’s atmosphere first before the sails may be utilized. The project would be dead in the water if it was too heavy to be transported.

So, why did the IKAROS satellite use electricity flow throughout its membrane? This is because the liquid crystal panels became reflective when electricity flowed through them, and no electricity made the sunlight pressure more diffuse. When you control the electricity flow through specific portions of the solar sail, you can control where the sunlight mainly impacts, allow the spacecraft to change orientations.

Though the deployment of the IKAROS satellite was only to test the viability of solar sails (as this satellite did not have a specific target destination), it proved that solar sails are a potential method of travelling deeper into space. For example of attainable speeds, The Planetary Society’s LightSail spacecraft is equipped with 32-square-meter solar sail is capable of an acceleration of only 0.058 mm/s^2; however, after only a month’s time of continuous sunlight, the spacecraft will have an increased velocity of 549 km/s (about the same speed as a jet airliner traveling at cruising speed). Issues with more accurate steering abilities and slowing this bullet down remain a concern. Nonetheless, the IKAROS revealed that solar sailing can be an available method of propulsion through space.

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Mercury and its core | blog IV

Posted on March 20, 2022 by clviggiano

Measuring just over one-third of Earth’s diameter, Mercury is the smallest terrestrial planet in the solar system. However, relative to other worlds, Mercury’s core constitutes a very large part of its volume. Despite the vast difference in their scale, “Mercury’s inner core is indeed solid [and] very nearly the same size as Earth’s inner core,” according to NASA’s Goddard Space Flight Center. For comparison, Mercury’s core comprises about 85% of the planet’s volume, while Earth’s only about 15%. The leading theory to explain this discrepancy is that powerful collisions knocked away the majority of Mercury’s outer mantle. This hypothesis suggests that it was originally a larger planet whose core:volume ration was similar to that of other planets. 

There is still relatively little is known about Mercury—in fact, it is the least explored terrestrial planet. However, a joint mission between the European Space Agency and Japan Aerospace Exploration Agency is striving to provide more knowledge about the world. The mission, which launched in October of 2018, is called BepiColombo; it “Comprises two spacecraft: the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (Mio).” However, it will be 2025 before MPO or Mio reach Mercury, with the journey from Earth taking more than seven years to complete. It will be well worth the wait: this mission promises to provide insight into our closest-neighboring planet.

NASA/JPL
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