“To Earth, From Jupiter”

This is an old writing piece I did for an advanced creative writing class in university way back in 2018. I’ve always intended to make this a full solar system set, but life likes to get in the way. Maybe in the distant future I might, but not when university, especially final year, is looming over me.

To Earth, From Jupiter

The sun was only a hundred million years old when I began to form, the embryo of a gas giant. I wasn’t much to look at, at first, a bundle of rocks coalescing to form a solid core the size of your Earth. While I was the sole planet in the solar system, I wasn’t completely alone, for I had the proto-sun as my companion, competing for the copious amounts of hydrogen available to us alone. That ringed show-off you named Saturn formed shortly after. And no, it didn’t yet have rings—still a giant nuisance though, raining on my fun. If it weren’t for Saturn, I would have drawn as close to the sun as I dared, and it would be us alone, with all the hydrogen to ourselves. But no, Saturn had to form and nothing was the same after that gas giant began to steal more hydrogen for itself. Rude.

Listen, I was a crazy young bundle of tiny planetisimals running on young protoplanet legs to the Sun. I may have kicked out (or eaten) tiny forming planets and perhaps smacked one into magma-laden Earth, but I was starry-eyed, eager to get up close to the Sun, even if it would begin tearing away my hydrogen, a trail fading behind my still-growing bulk. Our mutual gravitational pull was too much to resist. I, a young, eager, child of the proto-planetary disk, had to cling close to my parent. And I would have if it weren’t for my pesky sibling, Saturn. Did it really have to yank me back like that? Did it have to drag me so far out that the sun became so small in my skies? Then again, that vain planet with its countless rings, probably just wanted someone like itself to keep it company. It wanted nothing to do with those runty “ice giants” beyond us. Y’know, Uranus and Neptune. Frankly, I didn’t care much for them either. Still rude of it to come up behind me like that and yank me back out beyond the frostline! Just unacceptable.

Amalthea: The Reddest Potato In Orbit Around Jupiter

Everyone knows you shouldn’t eat green potatoes, but what about red potatoes (no, this doesn’t include potatoes with red skins)? I’m not sure on that count, but this red potato would likely taste like, well, rock and a whole lot of radiation courtesy of its parent planet, Jupiter. When I say this moon is red, it’s red, considered as the reddest object in our solar system. It is a moon that is not much more than a pile of icy rubble with a very low density. The most significant feature on its surface is a couple of craters, named Gaea and Pan, discovered and imaged by the Galileo space-craft in the 1990s. Pan is the larger of the two craters, with a diameter of 100km and a depth of up to 8km. In contrast, Gaea is a crater measuring around 80km across with a depth of up to 12km.

A grayscale image featuring three of Jupiter’s moons as imaged by the Galileo space-craft in January 2000. Amalthea is the biggest moon in the middle, showing one of its huge craters.

Amalthea is the biggest of the four moons that orbit within the moon Io’s orbit; the other three are Adrastea, Metis and Thebe. Of them all, Amalthea orbits the closest to Jupiter at an average distance of 181,400 kilometres away from the gas giant’s surface. It orbits Jupiter at an average speed of 95,362km/hr, taking just under half an Earth day to complete one revolution. Considering Jupiter’s enormous gravitational pull, it seems odd that this ruddy moon has not been torn apart to this day. It’s pretty simple: its dinky size means that tidal pull from Jupiter’s gravity has minimal influence on Amalthea, so it can carry on merrily orbiting the gas giant behemoth. Nevertheless, with time, it will eventually meet its demise when its orbit decays to the point that it will fall toward Jupiter and be torn apart forever.

Voyager 1 image of Amalthea, taken in 1979. Credit: NASA/JPL.

On a final note, you might think that, because it is so close to its parent planet, it would have been impossible for anyone to spot it before Voyager 1 flew past it in 1979. To the contrary! In fact, this modest little moon was discovered in 1892 by Edward Emerson Barnard, who spotted it through his 91 cm refractory telescope while he was working at the California-based Lick Observatory, which at the time, was only four years old (built in 1888.) It might be a tiny moon of little note in most mainstream astronomy textbooks and books in general, but it has been known since horse-and-carts were still in vogue.

To round off this post, enjoy a beautiful image of Amalthea casting its shadow on Jupiter as imaged by the JUNO space-craft currently (as of 2021) in orbit around the gas giant.

The shadow of Amalthea blots out a tiny patch of Jupiter’s vast red and white clouds. Credit: NASA/JPL-Caltech.

References:

“Amalthea Casts Shadow on Jupiter. (October 2017. Sci-news website.)

“Juno Completes its Eighth Flyby of Jupiter.” (September 2017. Sci-news website.)

“Amalthea” (Solar Views website)

Lick Observatory (Links to “About” Page)

In Depth: Amalthea. (NASA website)

By the Numbers: Amalthea (NASA website)

“SOLAR SYSTEM: Jupiter, Saturn, and Their Moons” (2005). Moore, P. In: Encyclopedia of Geology (pp. 282-289).

A-Z Quick Facts: Perihelion

Perihelion is the closest approach a celestial body takes to whatever it is orbiting, whether that be our sun (as in the cast of planets and comets, for example), or a planet (such as our Moon around Earth). The opposite of perihelion is aphelion, which is–you guessed it–the farthest point in a celestial body’s orbit around another object.

https://astronomy.swin.edu.au/cosmos/P/Perihelion

Astronomy Channel Spotlight: Space Mog (Dr. Maggie Lieu)

While many may know of the more popular and bigger astronomy Youtube channels like SciShow Space, Anton Petrov (‘What da Math’), and even Fraser Cain (Founder of the Universe Today website), as well as Astronomy Cast, there are some less well-known astronomy education channels floating around Youtube, especially those that are, for once, not hosted or created by only white people, with all due respect to aforementioned science communicators/science communication channels.

For example, Dr. Maggie Lieu, who is an astrophysicist at the University of Nottingham (United Kingdom), has a beautiful channel full of professionally-made and well-communicated videos related to space, accessible to people of all ages and expertise levels. She covers a range of topics ranging from foundational topics including how astrophysicists measure distances in space, as explained in this video:

Dr. Maggie Lieu explains how astrophyscists know how far away galaxies (and other space bodies including our Moon) are.

Or perhaps, you just want to go on a tour of the universe in a broad introduction to what is out there well beyond our own solar system, let alone our planet? From Earth to Alpha Centauri to the galaxy and beyond, Dr. Lieu takes you on a beautifully presented tour to the farthest reaches of the universe:

Dr. Maggie Lieu takes her viewers on a wonderful little tour of our universe.

She also covers questions that arise from headlines-grabbing news such as the time last year (and earlier this year) Betelguese dimmed very dramatically, much more so that astrophyscists are used to, making many people wonder if the star was about to go kaboom.

Dr. Lieu addresses the question of whether Betelgeuse is (or rather, was) about to go supernova.

Or what about that time that Venus rocked our world with the possibility of biosignatures in its atmosphere (which has since had much doubt cast upon it, due to rechecking of data and so on.)

Dr. Lieu also has plenty of videos on her channel that cover a range of questions and topics that are original and creative, including such questions as:

Is Covid-19 a space virus?

What colour is the universe?

What is on the far side of the moon?

And finally, here’s a fantastic and informative video where she introduces ten black astrophyscists you should know about.

Dr. Lieu introduces ten Black astronomers and space scientists that you probably have never heard of.

This Star is the Roundest Boi

Generally in astronomy, most round objects like planets, stars, and moons with enough mass to pull itself into a ball, are not perfect spheres. Even if a planet or star looks completely round, they usually have some degree of what astronomers call oblateness. Oblateness, in its simplest definition, relates to how “squashed” a round object appears. Planets (especially gaseous ones) and stars with a fast spin appear to be squished, their equators bulging out far more than their poles. Rocky bodies can have this too, including the dwarf planet Haumea that spins so fast that it appears as its famous egg-like shape. See enough long-distance photos of Jupiter and Saturn, and you’ll start to notice they look distinctly squashed too, thanks to their very fast spins and gaseous nature. The more technical term for this squished look is an “oblate spheroid”, a geometrical shape where the radius of the object’s equator is greater than at the poles.

A stunning long-distance shot of planet Saturn, appearing a light yellow with lighter bands of colour. Its rings throw a broad, banded shadow over the surface of Saturn’s north hemisphere. A tiny moon can be seen, immensely dwarved by the giant planet, under the rings on the right-hand bottom side of the planet. A second moon, a speck of white against Saturn’s surface, can also be seen under its rings. The planet’s “squashed sphere” appearance is obvious in the photo taken by the Cassini space-craft in December 2007. CREDIT: NASA/JPL-Caltech/Space Science Institute

But astronomy isn’t astronomy without the universe constantly giving us that one exception to the rule. So, then, meet the star with the boring and unwieldly name of  KIC 11145123, aka the roundest natural object astronomers have seen to date (since 2016, at least.) This, of course, implies that the radius at its equator and poles is the closest to equal astronomers have seen so far; in fact, the difference between the poles’ and equator’s radii is just 3km, give or take 1km. In comparison, the difference between our sun’s polar and equatorial radii is at least 10km. In addition, KIC 11145123 also has a slow rotational period of 100 days, which is a long time compared to our sun’s rotational period of just 25 days. However, even its 100 days long rotation should have given it far more of an oblate appearance than it actually does; in fact, researchers have estimated that it only has 1/3 of the oblateness that it should have, and they intend on researching deeper into the reasons behind its unusual sphericity that goes beyond just its rotation, as several factors can also play into how round a star or planet or even a moon can look, including gravitational influences of other stars and/or giant planets, magnetic fields, and stellar winds (for stars, anyway).

References:

https://solarsystem.nasa.gov/resources/932/a-stage-for-shadows/?category=planets_saturn

https://mathworld.wolfram.com/OblateSpheroid.html

This Star Is The Roundest Natural Object Ever Seen

A-Z Quick Facts: Opposition

You ever read an astronomy magazine or website and see some variant of this:

“Saturn will be at opposition in July 2020…”

“In September, such-and-such planet/moon will be at opposition…”

What are they doing up there? What are they opposing?

In astronomy, the term opposition simply means that a planet (or asteroid, or even the moon) is opposite the sun in the sky. As a result, the asteroid or planet or moon will set at sunrise and rise at sunset. An immediately obvious example is that of the full moon here on Earth: it’s opposite the sun in the sky, so it rises at sunset and sets at sunrise.

Concerning the planets, if Jupiter and/or Saturn (for example) are at opposition during a certain time of year, it simply means Earth is directly between the sun and aforementioned worlds. If you could stand high above the solar system, you would see that our planet is directly between the sun and, say, Saturn, as seen in the illustration from the Earthsky website.

Image showing what an opposition of Saturn would look like could you see the solar system from high above. Credit: NASA

References:

https://skyandtelescope.org/astronomy-terms/#o

https://earthsky.org/astronomy-essentials/what-is-opposition-astronomy

Europa and its Perpetual Glow-Up

Forget those cute little star stickers you used to have as a kid (or at least I did), because imagine an entire moon that glows in the night sky, and not because it is reflecting light from our favourite star in the universe. Rudolph’s glowing red nose pales next to this super-shiny moon orbiting a planet in our solar system, its light blue, but with little tinges of green and white. So, what exactly is this curious glowy moon that lights up some lucky planet’s night sky?

Do I suit this shade of blue? Credit: NASA-JPL Caltech

That moon is Europa, one of the so called Galilean moons of Jupiter, and its glow-up is, unfortunately, not from some benign cause; rather, it is all down to Jupiter’s radiation. Thanks to Europa’s proximity to Jupiter, this little icy moon “enjoys” a daily, relentless dose of high-energy Jovian radiation on its surface, the consequence being that its night-side would still glow even when facing away from Jupiter, as suggested by a series of lab experiments down by a science research team, with the paper released in November 2020.

Their lab experiment involved blasting Europan ice analogues (i.e. water ice with different compositions of salts) with high-energy electrons, and analysing the results’ various light emissions. They also related their findings back to earlier studies where they had discovered that with increased intensity of high-energy electron bombardment, the greater the spectral (i.e. light) intensity. The light emission was also noticeably stronger in ice containing epsomite, which is a very soft mineral (hardness of 2) with a chemical composition that includes magnesium and sulfate, as well as water. In contrast, samples with sodium chlorate or sodium chloride gave off the least light.

This study has several implications for future research and exploration of this frozen moon with its spectacular glow-up, especially more so with the potential launch of the Europa Clipper spacecraft maybe in the mid-late 2020s. For example, relating back to the amounts of light reflected depending on salt composition, scientists looking at the Europa Clipper’s imagery would be able to note darker patches as likely containing sodium chlorate and/or chloride, and brighter areas likely containing epsomite salts. These observations would be key to furthering whether Europa has the right conditions for life swimming somewhere deep under its icy crust. But, whether or not Europa’s glow could be detected by the space-craft’s cameras, is still yet to be determined or confirmed, but if it could, that could potentially be very breathtaking!

References:

https://www.nature.com/articles/s41550-020-01248-1 Laboratory Predictions for the night-side surface ice glow of Europa, Nature Astronomy, Nov 2020.

https://www.jpl.nasa.gov/news/news.php?feature=7779 Europa Glows: Radiation does a bright number on Jupiter’s Moon. Jet Propulsion Laboratory, NASA. Nov 2020.

http://www.physicsworld.com/a/jupiters-moon-europa-could-glow-in-the-dark Jupiter’s Moon, Europa, could glow in the dark, Physics World, Nov 2020.

Does Europa glow in the dark?

https://www.mindat.org/min-1393.html Epsomite, mindat.org

A-Z Quick Facts: New Moon

A “new moon” is considered by astronomers the first lunar phase, with the following crescent moon called a “young moon”. It is also the source of all the stunning total solar eclipses that many people (not me…yet) have had the immense fortune to experience. However, it is the slightly tilted nature of the moon’s orbit, at just over five degrees from the Earth’s orbital plane, that is a main reason we do not see a solar eclipse once a month.

In this phase, the moon is between the sun and Earth, and, thus, will rise and set with the sun through the day. So when the sun is at its midday height, so too is the companionable (if invisible) New Moon.

References:

https://astronomy.swin.edu.au/cosmos/N/New+Moon

https://earthsky.org/moon-phases/new-moon

Adrastea: One of Io’s Little Friends

Jupiter’s volcanic moon, Io, has four little friends keeping it company in its orbit: Metis, Amalthea, Thebe, and our star of today’s post, Adrastea. It is a humble smol, the tiniest of the quartet in Io’s orbit, at just 8.2km in radius, give or take 2kms. Owing to its place in Io’s orbit, Adrastea snuggles up nice and close to Jupiter, at just 129,000km away from the big boy of our solar system. That is very, very close and personal to Jupiter. How much so? Below is a stunning photograph from the JUNO space craft taken only 7000km from Jupiter’s cloudtops, but the planet is so huge that the view wouldn’t look much different even from Adrastea’s surface as it orbits the worldly behemoth in just seven hours.

A close up image of Jupiter’s clouds, showing a sea of swirling white, orange, blue, brown, and even pink, taken by the JUNO space-craft from only 7000km away! CREDIT: Gerald Eichstädt and Sean Doran (CC BY-NC-SA) based on images provided Courtesy of NASA/JPL-Caltech/SwRI/MSSS

Its size gives it another advantage: despite its closeness to Jupiter, it is too small to be affected significantly by its gravity; unfortunately, it is not immune to orbital decay, and eventually, this plucky little moon will fall into Jupiter, though how long this may take is not known.

References

https://solarsystem.nasa.gov/moons/jupiter-moons/adrastea/in-depth/

https://www.nasa.gov/image-feature/jpl/jovian-close-encounter

A-Z Quick Facts: Magnitude

In a nutshell, magnitude is used by astronomers to describe the brightness of a star as seen from Earth; negative numbers denote brighter stars compared to those with positive integers. So a star with -2 magnitude is brighter than one with +2 magnitude. Incidentally, magnitude isn’t reserved just for stars–it also applies to other celestial objects too including the Moon and the other planets in our solar system.

However, it isn’t quite that simple, as astronomers recognise two types of Magnitudes: Apparent Magnitude and Absolute Magnitude, with significant differences between the pair in how they are calculated and defined.

Absolute magnitude basically calculates how bright a star would be if plonked down at a distance of 10 parsecs (or 32.6 light years, with 1 parsec being 3.26 light years) from our sun. Ten parsecs is considered a standard distance for this, and another similar term that can be used to refer to absolute magnitude is absolute visual magnitude (Mv). Of course, to be able to define a star’s absolute magnitude, you first need to know its apparent magnitude.

Apparent magnitude, on the other hand, is a measurement of how bright a star looks from a particular location in space, such as the Earth. When we say, for example, that Sirius has a magnitude of -1.46, that’s its apparent magnitude, telling us how bright it appears from where we are. But that is not a fixed value, as another observer looking at it from, say, 100 light years from us would record a different apparent magnitude for Sirius, by virtue of being a different distance away from aforementioned star. However, were we to plonk Sirius ten parsecs from Earth, it would appear a lot less impressive (sorry Sirius!), reaching a maximum of just +1.4 (remember, positive numbers mean dimmer stars.)

Another example, one a lot closer to home, is the Sun: from where we observe it on Earth, it achieves an apparent magnitude of -26.8, but were we to punt it ten parsecs away from us, it would have an absolute magnitude significantly dimmer than even Sirius’, reaching a relatively paltry 4.83.

References:

http://astronomy.swin.edu.au/cosmos/A/Apparent+Magnitude

http://astronomy.swin.edu.au/cosmos/A/Absolute+Magnitude

https://www.space.com/21640-star-luminosity-and-magnitude.html

Seeds, M.A. 2013. Foundations of Astronomy.