The image shows the lower portion of Enceladus’ jets taken in 2010. Image and information gathered from the NASA website.
Enceladus, one of Saturn’s moons, got its name in Greek mythology because Saturn (Cronus) was the leader of the Titans. Despite its namesake, it is only about 310 miles across which is about the size of Arizona. Like Jupiter’s moon Europa, Enceladus has a subsurface ocean with an icy cover. Due to the icy exterior, Enceladus reflects so much light that the temperature is extremely cold. Additionally, the moon is in orbital resistance. This happens when several moons line up alongside their planet regularly and interact with one another’s gravity. An interesting part of Enceladus includes the fact the moon gushes parts of its ocean into space and scientists sampled it- discovering the moon has many of the chemical properties life needs to form.
There is a good chance you may have heard of Elon Musk’s space company SpaceX and the immense progress they have made in the rocket industry, completely obliterating the competition when it comes to number of launches per year. But have you heard of SpaceX’s newest triumph with their rocket, Starship? Starship is the biggest rocket to ever be built, standing at 397 feet with the booster attached and 165 feet with just the Starship on its own. Starship is designed to someday go to the Moon and beyond, maybe even bringing the first ever humans to Mars someday. What makes Starship so remarkable is that it is fully reusable. The booster is launched into space attached to Starship and then is discarded to shed weight once it runs out of fuel. These boosters used to just end up somewhere in the ocean and new ones would have to be created every time. Now the booster can control its descent and land pinpoint on target. This saves so much money and time, and enables SpaceX to keep launching more and more rockets per year. With Starship Launch 5, SpaceX actually caught the falling rocket out of the air with robot arms. This was a first to ever happen and a remarkable achievement of engineering, especially since they successfully completed this on the first try. What will the next accomplishments be that further our quest for the Moon, Mars, and beyond?
The James Webb Space Telescope is a telescope made to look deep into space. It is the largest telescope in space ever built. The telescope was launched into space during 2021. Due to its infrared strength it can see distant objects that light telescopes can’t. JWST was able to study the formations of galaxies and the universe. Early galaxies were able to be researched. Exoplanets and their atmospheres’ were also able to be studied and to determine whether they can support life. Although it has only been a few years since the telescope was released it has made important discoveries. Very clear pictures of distant galaxies have been taken as well new insight into how galaxies were formed.
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How do scientists know how old Earth and its rocks are? Modern humans have existed for “only” about 200,000 years, and modern science has existed for only a few hundred years (heck, how do we even know how long we as a species have existed?). So, how do scientists today know how old rocks are? The oldest rocks are about 4,000,000,000 years old, 20,000 times older than the modern human species.
One main way people know how old something is “radiometric dating”. Radiometric dating is the measurement of the decay of radioactive elements. Radioactive elements have varying numbers of protons/neutrons in their nucleus, causing them to decay into a more stable element by losing protons/neutrons. This decay is consistent and is measured in a time scale called half-life (the amount of time it takes a radioactive material to decay exactly half). It is possible to calculate half-life because the radioactive decay happens at a predictable rate.
So by observing how much radioactive material and daughter material are present, one can use the half-life of the radioactive material to calculate how old an object is. This can be used on rocks and organisms (a common element found in fossils: carbon-14 a radioactive isotope of carbon). Through radioactive decay, scientists are able to approximate how old something is, even if no organisms existed when the material was formed.
FIGURE 8.5 from The Cosmic Perspective (taken from Quizlet)
When looking at a diagram of our solar system, one likely notices that there are two visually distinct categories of planets. The smaller, rocky planets—Mercury, Venus, Earth, and Mars—are known as the terrestrial (Earth-like) planets, and the larger, more gaseous planets—Jupiter, Saturn, Uranus, and Neptune—are known as the Jovan (Jupiter-like) planets. The reason that the size and compositions of these planets are so strikingly different is mainly due to their distance from the sun.
The solar nebula that our solar system was born from contained different elements in different abundances that condense at different temperatures. 98% of the nebula was composed of hydrogen and helium gas, which never condense in space, accounting for the vast emptiness of our solar system. Hydrogen compounds like water, methane, and ammonia made up 1.4% of the nebula, and can solidify into ices at low temperatures. The final 0.6% of the nebula was made of rocks and metals, which can condense at higher temperatures than the hydrogen compounds.
Within the spinning disk of the collapsing solar nebula, small seeds of solid metal and rock grew into planetesimals—small pieces of planets—via accretion. At first, particles had to stick together electrostatically due to their small size, but eventually grew large enough to attract each other gravitationally. Near the sun, it was too hot for hydrogen compounds to condense, which explains why the terrestrial planets are made up of mostly rock and metals. Farther from the sun (beyond the “frost line”), the seeds that grew into planets also contained ices in addition to metal and rock. The fact that there was more condensable material farther from the sun partly explains why the Jovian planets are so much larger. In addition to having solid cores with more material, the larger masses of these planets allowed them to capture more gas gravitationally. This is why we think of these planets as being gas giants.
Source: the Cosmic Perspective by Bennet, Donahue, Schneider & Voit
One of the greatest questions of our solar system is how it came to be. A theory worthy of consideration has many criteria it must be able to fulfill: it should explain the motion of our celestial bodies, the two different types of planets, and the existence and location of asteroids and comets, while also allowing for exceptions to the general rules. The current reigning theory of our solar system’s formation is the nebula theory. The origins of this theory are traced back to German philosopher Immanuel Kant and French mathematician Pierre-Simon Laplace, who both proposed theories like this independently of one another.
In the nebula theory, our solar system began as a solar nebula, a cloud of cold, low-density gas made of elements produced by the big bang and nuclear reactions. This roughly spherical cloud likely spanned several several light years, and was too spread out for gravity to pull it together. So, we believe that the collapse was triggered by a shockwave from a supernova. After a strong force perturbed it, the gas cloud began to collapse, ultimately taking the shape of the solar system we know today.
While it collapses, the cloud heats up as the gravitational potential energy of gas particles is converted into kinetic energy. These particles crash into each other, releasing thermal energy. Additionally, because the radius of the cloud is decreasing, it begins spinning faster due to the conversation of angular momentum. Finally, the cloud starts flattening as clumps of gas collide and merge with each other. The new clumps have the average velocity of the original clumps, so the random motion of particles is evened out, and the cloud spins in a uniform direction. The hot, dense center of this spinning nebula will become the sun, and planetesimals will condense and grow about it. High energy radiation and solar wind will clear the nebula of excess particles, sealing the structure of our solar system.
Source: the Cosmic Perspective by Bennet, Donahue, Schneider & Voit
The Sun is mostly made of hydrogen and helium. In its core the two elements are fused together releasing light and heat in the process. The Sun’s has different layers (core, radiative zone, photosphere, convective zone, and corona). The corona is only visible from Earth during a solar eclipse and reaches millions of miles into space. The Sun also has events within itself such as coronal mass ejections, sun spots, and solar flares. These events can all have major repercussions on Earth such as affecting the power grid or internet. Understanding the Sun’s different phenomena is important in protecting the planet.
Pluto is most known for its famous debate: Is it a planet or not? As of 2006, Pluto is known as Dwarf Planet. A Dwarf Planet is a celestial body that orbits the Sun just like a regular planet; however a dwarf planet lacks a clear orbital path, sharing it with other objects. Pluto’s size is also wildly different that the other 8 planets, being smaller than the moon! Pluto was originally considered a planet because the term “planet” hadn’t specified its definition until more recent years with the help of new technology.
According to NASA, our Sun is a 4.5 billion year old yellow dwarf star composed of Helium and Hydrogen. It is the largest object in the Solar System with a diameter of about 1.4 million kilometers. The hottest part of the Sun is its core with a peak temperature around 15 million °C. Meanwhile, its surface – the photosphere – is significantly cooler in comparison with a temperature of only 5,500 °C. The Sun is the lifeblood of our solar system as it is the star’s gravitational pull that holds the Solar System together, keeping everything in its orbit. Additionally, without this star’s energy, life on Earth would not exist. The Sun’s importance is further demonstrated with how its presence also drives the seasons, ocean currents, and climate of Earth.
We have learned about radioactivity in class, and we hear about it in the news, but many do not have direct experience with radiation. It is a scary word that elicits a lot of fear in most; for example, concerns about safety have stopped nuclear power from gaining dominance despite otherwise being a superior source of electricity.
However, we are actually exposed to radiation on a daily basis. Radon in the air and ground is the source of most of our radiation exposure, and when buying a house it is very common to get a radon test (some places require it) to ensure the radiation exposure is not too high. There is also an amount that we get from cosmic rays, high-energy particles that originate from outside our solar system that make it down into our atmosphere. Something that we also may not think about are airplane flights, which actually expose us to a marginal amount of radiation. Finally, medical imaging studies are also a major source of radiation.
Radiation safety is highly regulated in most countries, and while it may sound scary and is certainly something to be mindful of, radiation is also all around us. Indeed, Carbon-14 is common enough for us to do radiometric dating, a useful tool in studying astronomy and many other fields of science.
