Saturn on Steroids

Posted on March 29, 2020 by alexsolarsystem
J1407b and its massive ring system (artist’s rendition)

Way out in the constellation Centaurus is a peculiar solar system 434 light years away that fascinates astronomers. The central star, named 1SWASP, is similar to our Sun in size and doesn’t appear to have any unusual characteristics for a main-sequence star. However, it was discovered in 2007 that 1SWASP is orbited by one enormous exoplanet when Eric Mamajek viewed a complex eclipse that showed the presence of a “Super Saturn.” This exoplanet (called J1407b) has also been called a “Saturn on Steroids” due to its enormous system of circumplanetary rings that are around 600 times the size of Saturn’s. For reference, if this planet changed places with Saturn we would see it’s ring system from Earth and it would appear 4-5 times as large as a full moon. Additionally, there are several gaps in the ring system that suggest the presence of large exo-moons. If anyone lives on those moons, they probably have an incredible view of the sky every night. I’m jealous!

Since the solar system is very young (only about 16 million years) it is theorized that the planet’s ring system will slowly diminish in size as time goes on. However, it appears that the rings orbit J1407b in retrograde motion, so this may allow for longer ring lifetimes than usual. Additionally, the rings may be able to be replenished by passing objects that get trapped in orbit. Whatever may happen to this “Super Saturn,” there’s no doubt that its rings are certainly amazing today!

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Sirens of Titan

Posted on March 29, 2020 by clairesspacejam

The lectures from this unit, especially chapter 11 about the Jovian planets, reminded me of one of my favorite books; Sirens of Titan by Kurt Vonnegut. The novel is a comical science fiction story that chronicles the origin of Malachi Constant, a profit predestined to be sent into space and return to start a new religion on Earth. Winston Niles Rutherford is a wealthy space explorer who, as a result of being launched into the chrono-synclastic infundibulum which allowed him to experience all space and time, was able to prophesize Malachi Constant’s life path. This life path includes spending time in the Martian army, on Mercury, and stranded in a deep cave on Titan, the largest moon of Saturn. Malachi’s time on Titan is arguably the impetus to his future as a religious figurehead. Although entirely based on science fiction, the description of living on Titan made me even more excited to learn in class that a probe from the European Space Agency has landed on Titan. Titan is one of the few bodies in the outer solar system to which humans have sent a landing probe successfully.

The cover of one of my favorite books; The Sirens of Titan by Kurt Vonnegut

In addition to exploring life in space, Vonnegut also delves into the concept of predestination. Rutherford was able to predict the entirety of Malachi’s life but could not allow him to forgo the necessary pain in the path to get there. At the beginning of the book, Malachi is a morally dubious character who tries to prevent these events from taking place. However, all of his actions end up leading him towards his destiny. This novel brings up a lot of the other moral implications of humans moving forward with space travel. Considering what I have learned in class, I choose to agree with Vonnegut and look ahead towards furthering the exploration of space. 

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The Real Villain in Pluto’s Demise

Posted on March 29, 2020 by avighitterman
The Planet Eris
Eris the goddess of strife and discord

The removal of Pluto as a planet was an emotional blow to anyone with a heart. It was a devastating betrayal leaving many asking questions that no one wanted to hear the answers to. While there were many reasons behind Pluto’s status change, the ultimate culprit is the dwarf planet Eris. Eris was discovered in 2003 as another object orbiting the Sun. While of comparable size to Pluto, it orbits at a much greater distance through the Kuiper Belt. The similarities between Eris and Pluto forced scientists to confront Pluto’s issues that they were previously able to ignore, or risk including Eris and other similar dwarf planets or trans-Neptunian objects as planets in the Solar System.

Not too much is actually known about Eris yet. We can guess that it is structured relatively similar to Pluto, and it does have some atmosphere in the parts of its orbit that it is warm enough for the atmosphere to exist. Interestingly, it was named after Eris the Greek goddess of discord, a fitting name because it caused disagreement about the status of Pluto. In addition, its one moon is named Dysnomia, Eris’s demon daughter. While the problems with Pluto’s planetary status were known before Eris, the discovery of this new dwarf planet was the catalyst leading to Pluto’s ultimate demise.

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Meet Makemake: The Dwarf Planet Partially Responsible for Pluto’s Demotion

Posted on March 29, 2020 by Jack

Pluto was discovered in 1930, and was classified as a planet. In 2006, as most of us probably know, Pluto was reclassified as a dwarf planet.

A significant amount of the population, whether justified or not, are opposed to the removal of Pluto from the official list of planets, primarily out of nostalgia for one of the celestial bodies they’d known as a planet their entire lives. So what prompted this reclassification?

In March of 2005, Makemake was discovered. It, along with Eris (discovered in July 2005) and other Kuiper Belt objects, triggered the assembly of the International Astronomical Union. They had a decision to make- expand the current list of planets, or add another classification of celestial bodies. We know how that turned out.

As I was reading about this decision, it occurred to me that I knew very little about Makemake, the dwarf planet that (with Eris’s help) demoted Pluto.

Makemake is roughly two-thirds the size of Pluto. It is slightly dimmer than Pluto, but still bright enough to be the second brightest known object in the outer solar system. Its orbital path extends beyond the farthest reaches of Pluto’s path, yet Makemake orbits closer to the sun than fellow dwarf planet Eris. Despite these similarities to Pluto- size, brightness, orbit- Makemake surprisingly lacks a significant atmosphere (Pluto has one, so we would expect Makemake to have one as well). The dwarf planet’s reddish-brown color led to the conclusion that it has a layer of methane at the surface (remember, no atmosphere).

Another similarity to Pluto is that Makemake has a moon of its own, nicknamed MK 2. This moon wasn’t discovered until April 2015 when it was observed by Hubble’s Wide Field Camera 3.

I personally have quite enjoyed reading about this dwarf planet, and it make me think…If the IAU assembly had voted differently in 2006, we would have more planets (I believe the vote would have upped the number to 12). There would be a good chance we would learn about the would-be new planets nearly as much as we discuss the terrestrials and jovians. We might even devote future exploration missions to these Kuiper Belt objects. What else might be different today if the dwarf planets were just planets?

Makemake and MK 2

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Wasp-76b

Posted on March 29, 2020 by jackfumagalli
An artist’s impression of iron rain on the planet Wasp-76b, 640 light years away
An artist rendition of iron rain on Wasp-76b via The Guardian

Two weeks ago, scientists observed an iron rain type phenomenon on an exoplanet known as Wasp-76b. Wasp-76b is a gas giant that is located approximately 640 light years away from the constellation Pisces. Wasp-76b orbits a different sun in its own galaxy. The distance between Wasp-76b and the sun it orbits is about 3% of the distance between Earth and our Sun. This leads to surface temperatures of over 2,400 degrees Celsius. 

Recently, scientists detected winds on the planet measuring up to 10,000 miles per hour and a steady iron rain pelting the planet. The picture above is an artist’s rendition of what the phenomenon would look like. Observers have been able to locate over 4,000 exoplanets in recent years and it will be very interesting to see what more new discoveries lie ahead.

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Could Pluto Become a Planet Again?

Posted on March 29, 2020 by katelynmofield

When I learned the order of the planets in elementary school, Pluto was still considered a planet. About 14 years ago, it was demoted to a dwarf planet. The International Astronomical Union has three criteria in determining planetary status. It is in an orbit around the sun, it has sufficient mass to assume hydrostatic equilibrium, and it has cleared the neighborhood around its orbit. To be a planet, you must have all three. Pluto actually orbits with other surrounding stuff in its “neighborhood”, meaning it can not count as a planet, and this, was given dwarf planet status. Jim Bridenstine from NASA argues that the IAU’s decision was unscientific, and was used as a means to keep the number of planet’s down to a manageable number instead of being forced to reevaluate the entire solar system. For now, Pluto remains a dwarf planet, but here is to Pluto lovers like myself: there is hope Pluto could once again be a planet.

What Is Pluto? | NASA
Photo Courtesy of NASA

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The Importance of Extrasolar Planets

Posted on March 29, 2020 by andyyangdk
A picture of several potential habitable worlds in the universe

Extrasolar planets, often called exoplanets, are planets that exist in other solar systems other than our own. These planets are very hard to find and study because their light is fainter than the light given off by the stars which they orbit. In 1992, astronomers Aleksander Wolszczan and Dale Frail noticed several planets orbiting the pulsar PSR B1257+12. They only detected gas giants similar to Jupiter, leading to the hypothesis that gas giants are more common than terrestrial planets. This hypothesis has been disproven because of the fact that these gas planets were simply easier to detect because of their massive size.

Studying these extrasolar planets could bring us much more insight on how the Earth came to be and what changes we may potentially see in both our solar system and our planet. Perhaps there will even come a time where humanity will have to travel from one habitable planet to another every few millennia because of the limited timespan of habitability for each of these planets. I personally believe that for humanity to live forever, we will have to create a planet-like space ship that simply floats in space, away from stars, black holes, and anything else that may easily destroy the spaceship.

Who knows? There may even be a human-like creature on some of these planets out there in the universe that are writing a blog for their astronomy class and wondering if there are others like them out there.

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Big Planets’ Moons and Life Outside “Habitability”

Posted on March 29, 2020 by remieri
A diagram of the Sun’s habitable zone. Note that it includes Earth, and maybe Mars and Venus, while explicitly excluding the Jovians and their moons.

Astrobiology has long relied on the concept of a “habitable zone”, that is a zone around a star that is the right distance from said star to hold liquid water, and therefore life. This concept is absolutely valuable, especially insofar as it allows us to classify new exoplanets and identify potential exoplanets that may host life. However, we don’t have to leave the solar system to realize the limits of this concept, and how it potentially forecloses the search for life in many other environments.

The first key limitation of the habitable zone is that it assumes heat originates solely from the central star. By looking at the Galilean moons, we can immediately see that that assumption is flawed. Europa and Ganymede both are far outside the habitable zone, and both have liquid water beneath their surfaces. How? Tidal heating. As the moons pass by each other, and orbit Jupiter, differences in tidal forces heat the moons to the extent that liquid water becomes possible. This is critical since these moons are among the best possible candidates for life within our solar system, with the conditions of the subsurface oceans being reminiscent of what we think Earth looked like around the start of life. The existence of liquid water on these moons indicates that a focus on habitable zones may preclude an examination of all possible bodies on which life may exist

The second key limitation of the concept of the habitable zone is the assumption that liquid water is a necessary prerequisite to life. While this certainly maps to our understanding of life on Earth, it is theoretically possible that life could exist using methane or some other compound as the key ingredient. This is important, since methane can exist in liquid form far outside the bounds of the “habitable zone”. One example of a body where this life could exist is Saturn’s moon Titan, where while it is quite cold, there is a significant amount of liquid methane. Whether or not life could exist in an environment like this is an open question, but these solar bodies provide key challenges to the concept of the habitable zone.

While life likely won’t be found on any of these bodies (nor Enceladus, a moon of Saturn with liquid water and organic compounds), they provide important theoretical challenges to the concept of where we think life can exist. As we seek life elsewhere, we should consider the habitable zone as important, but remember that astronomy can be very diverse, and a larger variety of environments may support life than we initially expect.

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What do we know about exomoons?

Posted on March 29, 2020 by Avery Bradley
Artist’s depiction of an exomoon candidate

Unfortunately, this question has an easy answer: not much. So far, no exoplanet has been confirmed to have a moon, even though scientists are detecting planets the size of the Jovians. Even though nothing has been confirmed, however, there have been some interesting potential discoveries. We say potential because again, the systems are so far away it is hard to confirm anything.

One astronomer from the University of Padua in Italy, Cecilia Lazzoni, claims she found two giant exomoons. In both cases, the planets are about 11 to 13 times as large as Jupiter, and their moons are around Jupiter size. The question is if these systems can even be understood as planets and their orbiting moons. Some say these planets could be classified as brown dwarfs, objects that can only complete half of the proton-proton chain and thus don’t achieve star status. Brown dwarfs are normally classified as 13 times as large as Jupiter, but the definition is completely clear. If the object is a brown dwarf, then the moon could actually be a planet. Another explanation for these systems could be calling them binary planets, similar to the idea of binary stars.

Other researchers from Columbia University claim to have evidence of an exomoon that is around Neptune size, orbiting around a planet several times as large as Jupiter.

This kind of discovery is exciting because, even if they aren’t called exomoons but end up being planets, they force us to expand how we classify and think of extrasolar systems. Additionally, similar to how astronomers consider Europa and other Jovian moons as possibilities for containing life, some consider exomoons as candidates for life outside our solar system. Dr. Phil Sutton from the University of Lincoln said,

“These moons can be internally heated by the gravitational pull of the planet they orbit, which can lead to them having liquid water well outside the normal narrow habitable zone for planets that we are currently trying to find Earth-like planets in…I believe that if we can find them, moons offer a more promising avenue to finding extra-terrestrial life.”

Exactly like our Jovian moons! So although exomoons might offer possibilities outside of what we know about our own solar system, we can still apply the knowledge we find in our solar neighborhood to other systems far, far away.

Sources: Have Astronomers Detected Exomoons at Last?, Exomoons May Be the Best Place to Search for Life

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Jovian Planet Interiors

Posted on March 28, 2020 by Emily Chen
Comparing the interior structures of the Jovian planets

The Jovian planets are often called “gas giants,” making it sound as if they were entirely gaseous. However, this name can be misleading, as it is true Jupiter and Saturn became giant primarily because they captured so much hydrogen and helium gas, but their strong gravity compresses most of the “gas” into forms of matter quite unlike anything we are familiar with, and Uranus and Neptune are made mostly of materials besides pure hydrogen and helium.

A spacecraft plunging into Jupiter would quickly be destroyed by increasingly high temperatures and pressures, as demonstrated when the Galileo spacecraft dropped a scientific probe into Jupiter in 1995, the probe only survived to a depth of 200 kilometers, about 0.3% of Jupiter’s radius. As a result, we can only learn about Jupiter’s interior through a combination of theoretical modeling and laboratory experiments. This has indicated that Jupiter has fairly distinct interior layers, with the layers not differing much in composition – all being mostly hydrogen and helium except for the core – but differing in the phase of hydrogen. Beginning with the outermost layer, the cloud-tops, temperatures stand around 125K and atmospheric pressure is about 1 bar – same as the pressure at sea level on Earth. Continuing down, the second layer is liquid hydrogen at a scorching 2000K and a pressure of 500,000 bars at a depth of 7000 kilometers. Then, at a depth of 14,000 kilometers, pressure increases to 2 million bars, forcing hydrogen into a compact, metallic form. This layer of metallic hydrogen is by far the largest layer, conducting electricity quite well and generating Jupiter’s magnetic field. Finally, we reach the core, a mix of hydrogen compounds, rocks, and metals compressed to an extremely high density that while the core may be about the same size as Earth, it contains ten times as much mass.

Saturn has the same basic layering as Jupiter, but its lower mass and weaker gravity make the weight of the overlying layers less than Jupiter. However, Saturn has thicker layers of gaseous and liquid hydrogen and a thinner and more deeply buried layer of metallic hydrogen. Uranus and Neptune have somewhat different layering as their internal pressures never become high enough to form liquid or metallic hydrogen, so they only have a thick layer of gaseous hydrogen surrounding their cores of hydrogen compounds, rock, and metal. Interestingly, this core material may be liquid, making for very odd “oceans” buried deep inside. The cores of Uranus and Neptune are larger in radius than the cores of Jupiter and Saturn, although the same mass, due to being less compressed by their light-weight overlying layers.

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