Black holes are regions of spacetime where gravity is so strong that nothing can escape. I have always found the idea of black holes because they can be hard to understand or conceptualize. A weird fact about black holes is how hot they are on the outside and how incredibly freezing they are on the inside. Just outside a black hole the temperature is very high but the interior of the black hole is around one millionth of a degree above absolute zero.
There are four types of black holes: stellar, intermediate, supermassive, and miniature. They all form in different ways and are all mysterious.
We have all heard of climate change but what does it really mean? Climate change can be explained by the change in temperature and weather patterns that are occurring over long periods of time. Humans are at fault for climate change because we continue to burn fossil fuels like oil and coal. Burning fossil fuels leads to greenhouse gases being released into the atmosphere. These greenhouse gases trap the sun’s heat in the atmosphere and raise temperatures on Earth.
How can we stop global warming? The world need to start cutting emissions. We can do this by switching to renewable energy like solar and wind power. These systems eliminate use of fossil fuels.
You can walk/bike more. By lowering the use of your car you are lowering your carbon footprint.
Save energy at home by installing solar power and LED lights around your home. Wash your laundry with cold water and let your clothes air dry instead of using your dryer.
Eat your vegetables! Eating plant based reduces greenhouse gas emissions and requires less energy.
The Universe is expanding – and expanding at a rate that is accelerating. Based off simple knowledge of physics, one would assume that this would be the opposite. The Universe should be shrinking over time as gravity slowly pulls billions of galaxy clusters, galaxies, stars, and solar systems towards each other on an inevitable collision course. But this is not the case, proven by measurements of the Hubble Constant and the Cosmic Background Radiation.
This is the cosmic background radiation. What you are looking at is essentially a map of the entire Universe, with the more dense areas as yellow/orange/red and the less dense as light/dark blue. The CMB originates from a critical moment in time when the Universe was just 300,000 years old. At this time, photons could interact with electrons interchangeably, creating charged ions. But after enough time, after 300,000 years, the Universe had begun to spread and cool so that these photons lacked the energy to jump in and out of electrons. It was at this moment in time that these photons became frozen in time, unable to change back into electrons, floating from that moment in time until the end of the Universe in space. What we are looking at above, more precisely, is an exact image of the Universe’s density almost 14.3 billion years ago, which should closely resemble the density and distribution of matter today as it is the space between galaxies that expands, not the galaxies moving themselves.
Directly above is a diagram demonstrating the Hubble Constant. Charted in the image are Type 1a Supernovae, a special, extremely bright solar entity that occurs when a white dwarf reaches a critical mass and collapses in on itself. The graph demonstrates an extremely linear, positive relationship between distance of the Supernovae and their velocity (measured using Doppler shifts). This chart proves the theory of the expanding Universe as it demonstrates that the further away an entity is, the faster it is moving – and moving away from us. The idea of the expanding Universe stunned astronomers for awhile, as it seemed very counter to what one would assume – wouldn’t gravity be pulling together all the galaxies once the initial energy and momentum of the Big Bang subsided? If this was not the case, then there had to be some other force at play pushing space apart.
The answer is dark energy. Dark energy is mysterious, something that has stifled astronomers and physicists and mathematics for decades. We don’t know very much about what creates it, how it interacts with matter, and what properties it has; however, two things are certain. It is this dark energy that is propelling the universe to expand, and expand at an accelerating rate. This is because the amount of dark energy is actually increasing over time, making up about 68% of all the matter in the entire Universe at this time. Note that dark energy is not actually “dark”, rather the term is used because knowledge about the entity is unknown.
Although it may take several chains of logic and evidence to come to the conclusion, and lots of research, it is quite clearly evident that the Universe is expanding, and accelerating as well – we just don’t know why. For this reason, the origins, details, and principles of the expanding universe is one of the largest questions hovering around astronomers today.
The sun has been around for 4.603 billion years, about one third of the entire duration of the universe. With a mass 330,000 times greater than Earth and a radius 108 times larger (source), the sun is a very massive object (though not that large when compared to other stars). Have you ever wondered what powers the sun, what keeps the sun burning bright and able to create heat waves on Earth, 92 million miles away?
The answer is nuclear fusion. You may have heard of nuclear fission, used in nuclear power plants to generate energy. Nuclear fusion is a very different process than nuclear fission. While nuclear fission involves the breakdown of radioactive atoms, nuclear fusion involves the combination of two radioactive atoms (source). Both processes create huge amounts of energy, but fusion is a much more powerful and stable source for the Sun.
Einstein’s famous equation e=mc^2 highlights how fusion works. Essentially, in a process known as the proton proton chain, protons and neutrons combine to form helium, effectively converting a very small percentage of their mass into energy (source). This is possible because, as Einstein stated, energy equals mass, so at extreme temperatures mass equals energy and vice versa. This is how stars fuel themselves. Eventually, however, a star will run out of mass to convert into energy using the proton proton chain, leading to the creation of a red giant. This will eventually happen to our Sun in 5 billion years.
Mars has been of interest because of evidence that it may have once supported life. NASA’s latest rover, Perseverance, has been sent to Mars to look for signs of ancient life. A big part of this endeavor is sending samples from Mars back to Earth for more detailed study. If successful, the Mars 2020 mission […]
Figure 1: Concept of a fusion-powered rocket developed by a NASA-funded startup known as Princeton Satellite Systems (PSS).
Nuclear fusion-where the nuclei of two atoms combine to establish a new atom-serves as the primary process that powers main sequence stars (like our Sun). For stars, nuclear fusion most commonly occurs with two hydrogen atoms fusing to form a helium atom. The result of such fusion processes is the output of great amounts of energy. So, as every great rocket scientist should ask: can nuclear fusion be controlled in a manner that it can safely propel a spacecraft through space?
According to Michael Paluszek (President of PSS), fusion-driven rockets the size of several refrigerators can one day take humanity to other planets in our Solar System. Though there are large fusion reactors under development with the objective of generating hundreds of megawatts of power, Paluszek’s smaller scale generator seeks to generate only around 10 to 12 megawatts (mW). However, this is a much lighter generator that could cost around $20 million (compared to the $20 billion experiments).
PSS’s fusion rocket seeks to utilize low-frequency radio waves to get a mixture of deuterium and helium-3 up to a temperature suitable for fusion to occur. Once this is attained, plasma is produced, and a generated magnetic field contains this plasma within a ring. Some of this plasma can eventually escape this ring and fling out of the rocket nozzle at a velocity of at most 25,000 km/s (or 55.9 x 10^6 mph). Finally, by conservation of momentum, the ejection of this plasma can drive the rocket forward at extremely high speeds.
How are these characteristics better than the current propellant-driven systems that we use today? Well, Paluszek mentions that, with current technology, a round-trip mission to Mars would take about 2 years, whereas spacecraft with six 5 mW fusion rockets can accomplish the same trip in about 310 days. From an electrical perspective, the New Horizons mission by NASA had only 200 W of available power for communications and instrumentation once it reached Pluto. A spacecraft equipped with just one fusion rocket can reach Pluto with approximately 500 kW of power (2,500x more power).
Therefore, nuclear fusion offers a great opportunity to expand humanity’s reaches into space as it can provide greater amounts of thrust and more power to fulfill the electrical needs of a spacecraft and its instrumentation. Such a step is needed to go further into space as we have essentially reached (or nearly reached) the maximum potential in which current propellant can produce. If fusion rockets can be successfully developed and refined, humanity can explore the once impossible to reach areas of the Solar System.
Computer-generated image of a white hole, via Space.com
Most people by now are familiar with the term “black hole”- a body of high mass with a gravitational pull so strong that nothing which enters can escape from it. The idea of a black hole was born from Einstein’s general theory of relativity.
Also born from Einstein’s mathematical equations, however, is the much lesser-known “opposite” of a black hole: the white hole. White holes are the opposite of black holes in both a mathematical and literal sense. Whereas a black hole does not allow any particle which enters to escape, a white hole prohibits anything from entering and ejects everything within it. Thus, light is only capable of leaving a white hole resulting in a highly radiative body.
Unfortunately, white holes currently are just a mathematical theory; scientists have not found any white holes existing in the universe. But, they do have a potentially important role in explaining the origins of our universe. Some scientists theorize that the big bang was actually a supermassive white hole. Unlike black holes, though, white holes are only visible for a short period of time during the event itself. Once its content is ejected, the white hole ceases to exist.
In class we discussed one potential theory of the moon’s formation that is the favorite within the scientific community: the giant impact hypothesis. The theory states that a Mars-sized body (Theia) crashed into the Earth ejecting pieces of a young Earth’s rocky crust into space. Gravity from the remainder of Theia’s core drew these particles together, eventually forming the moon as we know it today.
Some doubt is cast on this theory, however, due to the fact that computer-simulated models suggest that more than 60% of the moon’s materials should come from Theia, but the composition of the Earth and Moon are nearly identical. Some scientists believe they answered that concern 2 years ago when they found that the composition of rocks from the deep lunar mantle better matched those of the theorized Theia.
Despite its support within the scientific community, two other moon formation theories have achieved relative popularity, though more gaps exist in their explanations.
Co-Formation Theory: Some scientists believe that the Moon formed at the same time as Earth, similar to other moons and their parent planets in the solar system. Such an explanation would explain the similar composition of the Earth and Moon, since both would have formed from the same early solar system materials. But, it does not account for the differences in density between the Earth and Moon.
Capture Theory: Other scientists theorize that the Moon was formed elsewhere in the universe and the Earth pulled it into its orbit as it was passing by. Such a method has been observed elsewhere in the solar system, including two martian moons. The capture theory has difficulties explaining both the size and nearly perfect spherical nature of the moon.
An image of a Maat Mons taken by the Magellan Spacecraft using simulated color.
The Himalayas might be considered the most impressive mountain range on Earth, but what about other geological formations on planets around the solar system? Most famously, Olympus Mons is the tallest mountain in the solar system, located on Mars at 21229 meters, and about 2.5 times the size of Mount Everest. Alternatively, while not as seemingly impressive as Olympus Mons, Venus itself also contains mountain belts which are comparable to the Himalayas on Earth, and the main mountain belts are the Akna Montes, Danu Montes, Freyja Montes, and Maxwell Montes. It’s important to consider the different factors that led mountain ranges such as those on Venus to develop and why they differ from those found on other worlds in our solar system.
The mountain belts on Venus most likely developed in a similar way to those on Earth, where large parts of the lithosphere were compressed from their sides, resulting in land folding upwards. However, a very noticeable difference when observing mountains on Venus would be the far steeper slopes and cliffs. The surface of Venus is extremely high, at around 460 degrees Celsus, which results in no water or ice present on the planet. Without running water or moving glaciers, erosion of the steep mountains was unable to occur as it did on Earth, causing this major observable difference. In addition, rifts are also present on the Venusian surface, resulting from volcanic activity; however, just as the mountain ranges differ, rifts on Venus also differ as very little erosion has occurred due to the lack of water or ice. It’s interesting to consider the different reasons for why geological formations differ on other planets, as well, it’s important to consider how we would have to account for differences in geology if attempting to live on different planets in the future.
It may be hard to believe, but in all technicality, everything in the solar system, including humans, are born from star dust.
Let’s start at the beginning, at the big bang. The matter released from the big bang made up the first generation of stars, only containing the elements hydrogen and helium. Eventually, when the cycle of these stars living and dying and being reborn progressed, a small amount of matter in the universe was converted into other elements.
The current hypothesis on how our own solar system was created is the nebular theory, which starts with the idea that our solar system was created by the collapse of a solar nebula, which is a large cloud of gas. This nebula was formed by the cycle of stars living and dying producing recycled star material. At this point in time, science believed that the matter of the nebula still contained 98% helium and hydrogen, but 2% of other elements. Science believes that Earth, as well as the other planets in our solar system are mainly made up of this other 2%.
So in short, our entire solar system is made up of recycled star material, hence we are born from the stars. It may be strange to think, but in all technicality everyone on Earth is really just a descendant of the stars, and every atom in their body originated from one. Imagine if we could trace our individual atoms back to specific stars, and know which stars we are born from, now that would be a lot of fun!
