Pluto: If Size Doesn’t Matter, What Does?

Posted on April 9, 2023 by dougkyles422111
Protestors in Favor of Pluto’s planetary status. CNBC

Pluto is one of the most underestimated discoveries of our solar system. What we expected to be a simple ice ball comet-like object in the very outreaches of our solar system ended up becoming one of the most interesting planetesimals that tell us a complex geology category. Many will know Pluto for its classification as a planet, and then revocation of that category and the placement within a new one- dwarf planet. Ultimately, I was surprised to learn throughout namely chapters 11 and 12 that the boundaries of the terminology we use for solar system objects is quite arbitrary. There are always exceptions to the rule, for example as soon as we identified Pluto as a dwarf planet we posed the difficult question if the likely many many objects in the outer solar system are considered dwarf planets as well. When we look closely we can really only distinguish many of these outer objects by size, which is not a good differentiator because it is all relative. Many people are very heated in the debate on Pluto’s planetary status, with many (Like UTK’s Dr. Littmann) claiming we should keep it in the relatively arbitrary dwarf planet category for a unique reason: designating Pluto in this special category warrants it the attention it most likely deserves due to its unique geological story. This is a reason that I believe has some validity, but its irrelevance to the physical factors of Pluto essentially proves these categories are arbitrary.

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The Loneliness of Rovers

Posted on April 9, 2023 by 88bw
This is an illustration of what the Opportunity rover must have looked like as it traveled across Mars for 15 years.

Throughout this semester in ASTR2110, I have been reminded about how small we are compared to the universe. While this can be both a deflating and motivating perspective on our approach to astronomical study, I think it is undeniable that the rovers on Mars are unimaginably lonely during their stints on the red planet. I was reminded of these machines’ presence during a short YouTube video that shows the Curiosity rover singing itself “Happy Birthday” because it has no one else to celebrate with. It’s silly to anthropomorphize rovers that are tens of millions of miles away, but it makes me appreciate the work that the rovers do even more.

Curiosity was sent to Mars in 2012, and it’s nice to remember that for a few years, it got to share the planet with the Opportunity rover. The Opportunity rover is currently the standout success of our history with Mars rovers; Opportunity survived for nearly 15 years and may have lasted longer had a dust storm not covered the rover’s solar panels. While they never intended to cross paths, it is heartwarming to know that we have reached levels of success that ensure that we have at least two operational rovers on the planet now (Curiosity and Perseverance). I have wondered why NASA isn’t sending Curiosity to Opportunity’s site to help recover the hardy rover, but there are plenty of reasons. First of all, there is simply too much distance between the two rovers. Secondly, Curiosity was not built to be a rescue rover, so it may be futile in its rescue efforts if it ever made contact with Opportunity. Finally, astronomers have carefully planned out the missions and routes that these rovers take; a massive detour for Curiosity would ruin decades of planning behind Curiosity’s survey of Mars.

These sorts of thoughts confirm the amount of deliberation and careful planning that support the success of these rover missions. It would be wishful thinking to assume that these rovers can just roll about as they please, but it is a nice reality check to remember the precise commands and plans that govern the rovers that are the fruits of massive funding and human resources.

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Halley’s Comet

Posted on April 9, 2023 by sahilreddy2

Giotto Spacecraft Approaching Halley’s Comet

Halley’s Comet has the ability to completely destroy a city. Until learning about this comet in a previous homework assignment I never realized the true devastation even a comet of this size could cause on the earth. Halley’s Comet most famous observation occurred in 1066 where it was said that shortly before the invasion of England, William the Conqueror saw the comet and believed that it ensured their success in battle. Later as it was observed in the 1500s and 1600s, Edmund Halley in the 1700s determined that the comet would return every 76 years, and thus it was named after him once he passed away. When Halley’s Comet returned to earth in 1986, we were finally able to get proper images like the one above as we had spacecraft to take them. Also, once it returns in 2061 the comet will be on the same side as the sun and thus it will be much brighter than in 1986. Halley’s comet is one of the larger comets as it is about 15 miles in diameter, however because of the gravitational forces of the Sun and other planets it is very unlikely that it would ever impact any planet. Thus, these comets aren’t something we should worry about wiping us out as it is truly a miniscule chance that it would happen, and rather we should admire and observe them as they pass by us in the cosmos.

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The Outer Solar System

Posted on April 9, 2023 by dromalley
Pluto, formerly the 9th planet 😦

For this blog post, I’m going to be taking you on a journey through the outer solar system, beginning with what’s usually the last stop on the tour: Pluto. Pluto, formerly a planet, is now classified as a dwarf planet, orbiting at a distant 39 AU from the Sun in the dim outer reaches of the solar system. This region, known as the Kuiper Belt, is home to at least dozens of similar objects, with many more almost certainly lurking in the darkness.

Beyond the edge of the Kuiper Belt the solar system is largely devoid of anything until its boundary: the heliopause, the spherical boundary where solar radiation is in perfect balance with interstellar radiation. Beyond this, the occasional particles in the vacuum of space have an extrasolar origin, and it marks the boundary of interstellar space.

The Heliopause is the boundary between our Solar System and interstellar space

Even further than this, however, extending as far as 100,000 AU from the Sun according to some estimates, is the Oort Cloud, a spherical shell of small icy bodies whose existence is predicted to be the source of long period comets. These distant comets are the furthest objects still bound to our solar system, although at such extreme distances any connection is tenuous, and represent its final limit.

The Oort Cloud, the furthest objects “in” our solar system
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Naming Extrasolar Planets

Posted on April 9, 2023 by 88bw
This image by NASA shows 51 Pegasi b revolving around its sun, 51 Pegasi. They were discovered in 1995, and I see it as an example of an uninspiring, unversatile naming system.

Ever since we learned about the naming themes with the Jovian planets’ moons in class two weeks ago, I have been interested about how astronomers have managed to not run out of naming themes for the vast universe as they discover more worlds. I thought that the Jovian planets took up most of the cooler themes with Shakespeare characters and Greek deity relations. Meanwhile, I often come across extrasolar planets with relatively unappealing names that are nearly identical to their star(s), such as the example of 51 Pegasi and its planet in the picture above. There is actually a rhyme to the reason though; this NASA article goes into depth about the traditional naming system.

All planets have designations, but only a portion of the known planets get a proper name like Saturn or Neptune. The designation naming system is very straightforward; there usually is a reliable naming catalogue like the Henry Draper Catalogue, and stars are named in the order that they are found. For example, the 165,321th star to be discovered would be called HD 165321. From there, the planets that orbit the star can be named in the order that they are discovered using the alphabet. In this case, the star itself is considered “letter A” so the first planet to be discovered around HD 165321 would be called HD 165321 b. This raises the question of how they named planets that have more than 25 other neighboring planets in the same solar system, since you would run out of alphabets by then. In addition, this naming designation system also assumes (correctly) that in almost every situation, the star is discovered first followed by its respective planets.

It is exciting to see the article mention that the establishment of proper names is increasing in frequency. In fact, the article raised a naming contest as one such avenue for finding attractive proper names for planets that simply do not belong in our own solar system. I feel like these naming contests make astronomy feel more accessible to the common folk in an age where the communication of physics and astronomy is burdened by the barrier to entry of understanding the increasing levels of complexity in the fields. It harkens back to Dr. Tyson’s preface to our textbook where he emphasizes that the communication of science is of utmost importance in this day and age.

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It’s a bird! It’s a plane! No, it’s… Super Earth???

Posted on April 9, 2023 by groblesnieles727

Image by NASA https://exoplanets.nasa.gov/eyes-on-exoplanets/#/planet/GJ_15_A_b/

Within our solar system, there are three main classes of planets: terrestrials, gas giants, and ice giants. These planet types are reflected throughout the universe, with NASA categorizing these similar planets as gas giants (or Jupiter-analogues), Neptune-likes, and terrestrials (or Earth-analogues). However, within the universe, NASA also recognizes and classifies exoplanets within a fourth category: Super Earths.

Although the name seems to imply Earth-like characteristics, the Super Earth category only makes reference to the size of these planets. Super Earths can be as large as double the size of Earth, and ten times as massive. These planets can be rocky, gaseous, or some combination thereof, but the key detail is that they are smaller than Neptune-likes (although those on the extremely large end of the spectrum are sometimes referred to as mini-Neptunes or sub-Neptunes).

One such exoplanet is GJ 15 A b, depicted (hypothetically) above and discovered in 2014 by radial velocity. Although the category may have connotations of Earth-like characteristics, GJ 15 A b is only similar in that, dimensionally, it exists on a scale similar to Earth. Its radius is approximately 1.5 times that of Earth’s, and it is about three times as massive. However, its orbital period is extremely quick relative to Earth’s at only 11.4 days to orbit its parent star. Additionally, the surface temperature is described as super-heated, with NASA estimating its surface temperature at 530 degrees Fahrenheit.

Unlike Neptunians, Jupiter-analogues, and Earth-analogues, there is no planet in our system that fits the category of “Super Earth.” These planets could prove to be essential for research regarding planetary formation theories, but for now, we’ll have to settle for our own super Earth.

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Exoplanets!

Posted on April 9, 2023 by dromalley
A size comparison of several exoplanets to Earth from Caltech

Over the past several decades, the study of extrasolar planets, or exoplanets, has been one of the most rapidly advancing fields of astronomy and even science in general. With huge leaps forward that have been made in both technology and methodology, the number of exoplanets astronomers have been able to directly observe has exploded, with more than 5000 fully confirmed planets and thousands of candidates which may or may not be. There are a number of ways to identify exoplanets, but the two most common are by observing a transit (measuring how much of a star’s light and exoplanet blocks when it moves between us) or by observing the red and blue shift of the star as it orbits the system’s center of mass.

The radial velocity method relies on measuring the shift in light from the host star

Given the massive number of stars in our galaxy, and the apparent frequency of expo planets around other stars (about 1/5 of sun-like stars) estimates for the number of planets in our galaxy alone can top 100 billion. As we continue exploring the galaxy around us, and especially with new tools like the JWST, that number is sure to grow. With so many planets in our galaxy, its almost certain there are many, many habitable worlds, and it is very possible there may already be life on them.

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Space Potatoes!

Posted on April 9, 2023 by sadiekarr

(Diagram showing various asteroids, very potato shaped, you may notice)

As Dr. G says, “When I say Asteroids, you say Space Potatoes!”

But what exactly does that mean?

The reason we liken asteroids to potatoes is because of their shape (unfortunately, they do not taste as good as those beautiful starchy tubers) (Side note: in case you didn’t know [because I did not], a tuber is kinda like a root but not really. Apparently potatoes are tubers. You learn something new everyday). Because asteroids are so small, they do not hold enough gravitational force to mold themselves into spherical shapes like larger planets do.

You may notice that in the chart above the asteroid Ceres, however, looks very round. Ceres is a special case because it actually is large enough to have the gravitational force to make itself round. It is the largest asteroid in our solar system and accounts for ~1/3 of all mass in the Asteroid Belt. It’s such a large asteroid, it is actually a dwarf planet too!

Maybe now you’ll think of asteroids every time you have potatoes too 😉

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Bog 5 – Chelyabinsk Meteor

Posted on April 9, 2023 by constellationsarentreal

A relatively recent and frightening meteoric event occurred in the quaint city of Chelyabinsk in Russia on February 15, 2013. This incident is rather interesting since damage caused by the meteor was not due to impact, but rather violent shockwaves produced by the airborne-meteor’s explosion over the city. The explosion occurred when the meteor, roughly the size of a house, exploded 14 miles above ground, causing an intense flash of light and sonic boom which not only blew out windows within 200 square miles, but also damaged some buildings. Of the 1,600 people injured in the explosion, most attributed their injuries to shattered glass.

Picture of the meteor’s vapor trail after it plummeted through the atmosphere.

The Chelyabinsk Meteor was also a crucial catalyst for the creation of several agencies geared toward the detection of potential impact asteroids. Programs like The International Asteroid Warning Network (IAWN) and NASA’s Planetary Defense Coordination Office (PDCO) were established after heightened awareness of the Chelyabinsk incident. Even still, several programs at NASA, most notably the Near Earth Objects Observation Program, received more funding and attention. Since then, NASA has detected, identified, and continuously tracked thousands of asteroids. NASA also worked with the US Government to develop planetary defense plans against an imminent asteroid impact. In addition to the testing of computer simulations, NASA’s Double Asteroid Redirection Test (DART) space-flight mission successfully altered the orbit of an asteroid by butting it off course through kinetic-impact. Learn more about DART here.

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Lightning on Jupiter

Posted on April 9, 2023 by sadiekarr

How fitting that mysterious lightning has been observed on the planet named after the god of sky and storms!

Lightning on Jupiter has been reported multiple times over the years during multiple space missions: the 1979 Voyager mission, 1990s Galileo Jupiter mission, and again during the 2007 New Horizons mission. Now that we’ve got Juno (orbiter spacecraft) to keep an eye on Jupiter, more lightning and new information have been observed!

Besides being super freaking cool, Juno’s observations of lightning on Jupiter have revealed ammonia (rather than just water) in the planets storm clouds. For the longest time, we assumed that the lightning on Jupiter occurred in the same manner as lightning on Earth (convection). And that is mostly the case, but the observation of “shallow lightning” means that something a little different is going on.

Shallow lightning is a “form of electrical discharge [that originates] from clouds containing an ammonia-water solution,” rather than only water, like on Earth.

This video (which we viewed in class) simulates going through the clouds on Jupiter as bursts of shallow lightning occur. Pretty cool!

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