Eris is a trans-Neptunian object and is the second-largest dwarf planet in the solar system. It was discovered in 2005. It is .28 % the mass of Earth. Eris has one large moon, Dsymonia.It is about 96 AU away from the sun. Its orbital period is 559 Years. Its surface has methane ice. This shows that Eris has always been at the solar system’s edge.
Dr. Alan Stern is most known for his role as the principal investigator of the New Horizons mission to explore Pluto and the Kuiper Belt. Recently, Dr. Stern spoke at Purdue University on October 10, 2019, discussing and examining the topic of “What If We Return to Pluto?” During this discussion, he detailed many interesting facts about Pluto. For example, he mentions how before we had obtained clearer images of the outer planets, they had not realized how many of the rocks similar to the size of Pluto orbited the sun. We also discovered that Pluto is just one of many dwarf planets that are all very small in comparison to the rest of the planets. For reference, he compares Pluto to being only as large as North America. To some, this may seem notable, however he refutes this by showing how this may seem large but in the context and scale of planets, being as large as a continent is very small. He also explained the reasons why it was important to visit something so far away in our solar system. He discusses how before New Horizons, the best picture of Pluto ever taken was a blurry blob in space. Due to its distance, this is the best that could have been taken of Pluto and was even regarded as being revolutionary at the time. In contrast, pictures of Earth were incredibly clear and we were capable of depicting what was occurring on planets because of such pictures. Since Pluto was so far away, it was needed to explore further out to get a more accurate depiction of it. Scientific pioneers and explorers such as Dr. Stern are why our exploration of the solar system has reached these levels. Because of people like him, I am now eagerly waiting to see or even one day be a part of our world’s future chapter in space exploration.
Extrasolar planets can be difficult to detect because they are tiny, far away, and dim, but the Doppler Method provides an indirect way to find them. This method involves looking for alternating blueshifts and redshifts in the star’s spectrum, which reveal a star’s motion around its center of mass. This motion could reveal the presence of planets orbiting the star.
We can then look at how the star’s orbital velocity changes over its orbit. The slight changes in the star’s orbital velocity can tell us if it is orbitted by a planet. The planet’s gravitational tug on the star would cause these velocity changes.
The Doppler Method is effective because of its sensitivity. It can measure very slight doppler shifts, which can tell us about the presence of very small planets orbiting stars. However, because more massive planets have larger gravitational tugs on their stars, they are easier to detect. These stars have greater velocities as a result, which makes the shifts due to their planet’s tug easier to see. Also, planets closer to their star are easier to detect. These planets have shorter orbital periods, so we can analyze their orbits in less time.
Do you think the Doppler Method or the Astrometric Method is more effective? For which types of planets?
Kepler-16b was discovered when looking for exoplanets using the transit method from the Kepler mission of 2011. While looking at this data two stars were discovered to be in orbiting each other due to the dip in brightness of the system when they eclipsed. What was strange was even when they were not eclipsing each other the brightness of the system still dipped at irregular intervals, which indicated that they were at different points in their orbital periods when this happened and strongly suggested the existence of a third body. This ultimately led to the discovery that this exoplanet, Kepler-16b, was orbiting both stars and was the first discovery of a circumbinary orbit. Similar to the depiction to the planet Tatooine, home of Skywalker in Star Wars, but thought to be cold and gaseous without the ability to be inhabited. Additionally, it is thought to be about the size of Saturn and made up of half rock and half gas. Astronomers believe this discovery opens the door for a whole new opportunity to find life with a new type of system to look for.
Jupiter’s magnetosphere is by far the strongest. This is because of how thick its layer of metallic hydrogen is and its high-speed rotation rate. Its strength is 20,000 times stronger than Earth’s. It’s so large that it begins to avert the solar wind almost 3 million kilometers before it even reaches Jupiter. Jupiter’s magnetosphere in the sky would be larger than our full moon. Jupiter’s magnetosphere catches many more charged particles than Earth’s because it has another source of particles: Io, its volcanically active moon. This helps to create auroras on Jupiter, but these particles also generate intense radiation around Jupiter. These belts of radiation can be damaging to spacecraft.
The formation of our solar system helps explain the composition of the Jovian planets. Past the frost line, hydrogen compounds condensed into ices. The four jovian planets started as icy planetismals, but Jupiter and Saturn captured much more hydrogen and helium gas than Uranus and Neptune during solar system formation. This is probably because Jupiter and Saturn are closer to the sun, so the gases were less spread out at this distance and easier to capture. The planets capturing more of this gas became more compressed. Jupiter is very compressed, with extremely high internal pressure.
Jupiter’s interior layers are gaseous hydrogen, liquid hydrogen, metallic hydrogen, and then the core. The layers are named after the phase of hydrogen, which varies with temperature and pressure, but it is important to note that the layers also have helium in them. Saturn’s layers are similar to Jupiter’s except Saturn has a much thinner layer of metallic hydrogen because of its lower internal pressure. Saturn is less compressed because of its lower mass and gravity. Uranus and Neptune just have layers of gaseous hydrogen around their cores because their internal pressure is not high enough for liquid or metallic hydrogen to exist. However, the four jovian planets have cores of similar masses and compositions but different sizes because Jupiter and Saturn are more compressed.
It’s interesting how distance from the sun during solar system formation can have such an impact on the type and amount of material planetismals accrete. Jupiter and Neptune may be quite different, but they are pretty similar compared to terrestrial worlds like Earth.
***I have hyperlinks but for some reason they don’t show up unless you move the mouse over them.
Black holes are one of the greatest mysteries of our universe. However, using just a few concepts that we have learned in class, we can understand the basic constructs of black holes. A black hole is the result of a single point in space containing extreme mass (this point is called a singularity). Similar to how we observe planets and stars exert gravitational force on nearby objects, a black hole singularity exerts a very strong gravitational force. Additionally, we know that celestial bodies all have unique escape velocities that depend on the bodies force of gravity (which is proportional to M/(R^2)). Escape velocity is the speed which an object must reach in order to escape from a gravitationally bound orbit. Because a black hole singularity is a point of immense mass, it has an extremely high escape velocity at nearby locations in space. What we call a “black hole” is really the spherical area of space in which the escape velocity from the black hole singularity is greater than the speed of light. This means that inside the black hole, no light (or any other particle) can escape. Because no light can escape this sphere of space, the region of space looks completely black to any outside observer. This is why it is called a “black hole.”
Despite the relatively simple physics that describe the construct of a black hole, there are many aspects of black holes that are still mysteries to even the greatest physicists/astronomers.
Planet Nine is a hypothetical planet on the edge of the solar system. Its gravity would explain the weird orbit of objects beyond Neptune. It is predicted to be 5 times the size of Earth. It is assumed to be about 400- AU
The Scientists who created this hypothesis believe that the star formed much closer and was ejected by Saturn or Jupiter. It likely would have become a Gas Giant but it was flung away from the rest of the solar system.
The planet would be hard to find because there is very little light.
In 2019, researchers captured the first image of a black hole. They were able to do this by having all the major radio telescopes on Earth act together to simulate a radio telescope that was the size of Earth. Before this, we could only see indirect evidence of the existence of black holes. This particular black hole, at the heart of the Messier 87 galaxy, has the mass of 6.5 billion suns. This huge mass is due to the black hole’s gravity that pulls in all surrounding objects. This extremely strong gravity occurs because of how dense the black hole is, with matter being condensed into a relatively small area. Black holes usually form as a consequence of star death and are thought to be at the center of most large galaxies. Because of this, black holes help scientists study galaxies.
Hot Jupiters are gas giants that have orbital periods that are very close to their stars; often less than 10 days. Usually this means they are less than 0.1AU away from their stars which is one tenth the distance between earth and the sun. While scientists originally did not think giant planets could exist this close to a star since finding exoplanets Hot Jupiters have been found in large numbers. This is, in part, due to the fact that they are the easiest type of exoplanet to find with radial velocity (doppler) and the transit method. Scientists are still puzzled by the fact that Hot Jupiters exist as they are to massive to form at the origin of the system as the building blocks needed for it would not be enough at this distance. Some believe this is due to the fact the orbits of Hot Jupiters are excited to a very high eccentricity which causes them to approach the stars so closely that the orbital energy becomes tidally dissipated which shrinks and circulates their orbital pattern over time. Either way, it does seem as though our solar system exists as the anomalies without these Hot Jupiters.
