Jupiter’s New Moons

Yesterday, space nerds were alerted to the news that 12 new moons have been discovered in orbit of Jupiter. These are much smaller than Jupiter’s moon Ganymede, which is the largest moon in the Solar System and is larger than even Mercury. The point is that there are almost certainly no Ganymede-esque moons orbiting Jupiter that remain undiscovered.

But despite their small size, these moons do have some interesting features, as the article I read in the Guardian pointed out. The most interesting is the orbit of the moons. In general, Jovian moons orbit either prograde, i.e. with the orbit of Jupiter, or retrograde, i.e. against the orbit of Jupiter. The two inner moons discovered are prograde and nine of the other 12 are in an outer orbit of retrograde moons. But Valetudo, the 12th, which orbits in the retrograde group, actually orbits in a prograde fashion. The graphic below from the Carnegie Science Institute does a pretty good job of showing this.

Consider this your collision warning
Consider this your collision warning

Ultimately this means that at some point in the future, Valetudo will slam head-on collision style with another Jovian moon. And reportedly that will be so intense we will be able to see it from Earth. Bangin’. Catch is that it will not likely happen anytime soon.

As for the graphic above, I am of two minds. I generally like the use of colour. The bright green contrasts starkly against the red—though it should be pointed out it would fail a red-green colour blindness test. And then the interesting, but admittedly less interesting prograde and previously discovered Galilean moons are in more muted blues and purples, which puts them further into the background. It works nicely as a complete package.

But should it be on a deep blue background? Lots of space visualisations use black backgrounds, including my work and the work of others. But sometimes work that uses a white or otherwise light background could more clearly show things like orbits. It is difficult to say with certainty because of the lack of a light background for comparison’s sake.

The other thing that gets to me is the viewing angle of the orbits. Clearly we are looking neither dead-on nor from high above. And that makes it a bit more difficult to compare orbits. Of course these might not all be on the same plane because orbits are in three-dimensional space. But if the orbits were all shown from above, it would certainly aid with problems of foreshortening.

All in all, though, I shan’t complain because we have more moons in the Solar System. And who knows how many more smaller moons both Jupiter and Saturn have.

Credit for the piece goes to Roberto Molar Candanosa.

The Brightest Night Lites

Today is Friday. We all made it through yet another week. So let us look up into the evening sky tonight and see the Hertzsprung–Russel diagram in action. Or, we can take xkcd’s expanded version and just enjoy ourselves.

Alas, I too am in the lower right corner…
Alas, I too am in the lower right corner…

Credit for the piece goes to Randall Munroe.

Spanish Silver

A few weeks back now the Economist posted a graphic about the link between lead, silver, and the rise and fall of the Roman Empire. But not in the way you probably think. Instead, they graph the appearance of lead deposits in the glaciers of Greenland.

I believe that final Iberian power is meant to be the Moops.
I believe that final Iberian power is meant to be the Moops.

For the full explanation you should read the short article. But this piece was right up my alley. We have ancient history, economics, science, and a timeline. And all in one neat little chart.

Credit for the piece goes to the Economist’s Data Team.

Lunar Observations

Monday night I was doing some work outside and when I turned around to head inside I was struck by the brilliance of an object in the night sky. I had seen the Moon rise earlier in the evening, but this was far to the east. It was identifiable as a dot, not just a speck in the night sky. As I was now intrigued I went to grab my binoculars to see if I could see Venus.

Turns out I was wrong and it was Jupiter. But then I turned my binocular-aided eyes to the west and examined the Moon. That was then I decided to try and sketch my observations, as I had done with the Eclipse.

Unfortunately, it turns out it is far more difficult to sketch in the dark then under a still semi-sunny sky. But these are my attempts to digitise those observations. And as I sat and watched, I began to notice that some faint twinkling specks near Jupiter had also moved. After I came inside, I discovered that the movement and positions hewed close to the orbits of Jupiter’s moons Ganymede and Calisto. The moving speck near the Moon I had also observed was actually the bright star Regulus. (And to be fair, it had not really moved, the Moon had moved, but I was not redrawing the Moon.)

The Moon and Regulus. The cool part is the thin ring of one of the seas that could be spotted beyond the line separating lunar day from night.

Capturing the exact shapes of the lunar "seas" was difficult in the darkness.
Capturing the exact shapes of the lunar “seas” was difficult in the darkness.

Jupiter and two of its moons. The cool thing about Jupiter is just being able to see it as a round ball in space and not a distant twinkling speck.

Jupiter and two of its moons, as they orbit the distant planet
Jupiter and two of its moons, as they orbit the distant planet

Credit for these is mine.

A Wetter Midwest

Here in Philadelphia, I think yesterday was the first day it had not rained in over a week. Not that everyday was a drenching storm, but at least showers passed through along with some downpours and definitely grey skies. But what about my old home, Chicago?

Well, FiveThirtyEight turned to a longer-term look and examined how over the century the amount of rainfall in the upper Midwest has been increasing. We are actually looking at the same places the Post looked at a few days ago. But instead of political maps, we have rainfall maps.

This one in particular is weird.

Water water everywhere
Water water everywhere

I get why they have the map, to show the geographic distribution of the rain gauges that collect the data. And those are site specific, not statewide. But did the designer have to choose area?

We know that area is a less than ideal way of allowing users to compare data points. And as I just noted, a choropleth, even at say the county level, is out of the question. But what about little squares? Or circles? Could colour have been used to encode the same data instead of size? And then we would likely have fewer overlapping triangles.

I suppose the argument is that the big triangles make a bigger visual impact. But they do so at the cost of comparable data points across the Midwest. Maybe the designer chose the area of triangles because there were too few gauges across the country. I am not sure, but for me the triangles are not quite on point.

That said, the graphics throughout the rest of the article are quite good, especially the opening scatterplots. They are not the sexiest of charts, but they clearly show a trends towards a wetter climate.

Credit for the piece goes to Ella Koeze.

Knuckle Cracking

I used to work with a designer who was an expert knuckle cracker. So when I saw this article from the Guardian last week, I was hoping that it contained some kind of an illustration. Thankfully it did.

Pop goes the bubble
Pop goes the bubble

What I like about the graphic is its simplicity. The illustration does not add a lot of extraneous details in the hands or fingers. Instead it focuses on a three-step zoom into the joint between the fingers and the hands, showing how the bones connect and just what happens.

So Happy Friday, all. Just relax, lean back, and—made you want to crack those knuckles, didn’t I ?

Credit for the piece goes to the Guardian graphics department.

Warmer Winters

Philadelphia is expecting a little bit of snow today, 20 March. We should not be seeing too much accumulate if anything, but still, flakes will likely be in the air this evening. That made me think of this piece from just last week where the New York Times looked at the change in winter temperatures across the United States for the last almost 120 years.

Of course, I would be remiss if I failed to mention that climate change does not mean that temperatures always rise. Instead, while the general average trends upward, the curve flattens out meaning more extreme events on both the hot and the cold parts of the spectrum. (Actually, the New York Times covered this very subject well back in August.)

As a cold weather person, yeah, this isn't great…
As a cold weather person, yeah, this isn’t great…

Anyway, the map from the Times shows how the biggest changes have been recorded in the north of the Plains states. But the same general shift is subject to local conditions, most notably in the southeast where temperatures are actually a lit bit lower.

Credit for the piece goes to Nadja Popovich and Blacki Migliozzi.

Undersea Mining

Today’s piece isn’t strictly about data visualisation. Instead it’s a nice article from the BBC that explores the nascent industry of undersea mining. What caught my interest was the story of Soviet submarine K-129, which sank mysteriously in the middle of the Pacific. But that isn’t even half the story, so if you are interested go and read the article for that bit.

But that sinking may have created the beginning of the undersea mining industry. And so as I read on, I found a nice mixture of text, photography, and graphics explaining processes and such. This screenshot is a comparison of the size of an undersea mining zone compared to a land-based copper mine.

An undersea mine vs. a surface mine
An undersea mine vs. a surface mine

Some of the graphics could use some polish and finesse, but I do appreciate the effort that goes into creating pieces like this. You will note that four different people had to work together to get the piece online. But if this is perhaps the future of BBC content, this is a great start.

Credit for the piece goes to David Shukman, Ben Milne, Zoe Barthlomew, and Finlo Rohrer.

The 2017–18 Flu Season

Last week I covered the Pennsylvania congressional district map changes quite a bit. Consequently I was not able to share a few good pieces of work. Let’s hope nothing goes terribly wrong this week and maybe we can catch up.

From last Friday we have this nice piece from FiveThirtyEight looking at the spread of influenza this season.

Red is definitely bad
Red is definitely bad

The duller blues and greens give way to a bright red from south to north. Very quickly you can see how from, basically, Christmas on, the flu has been storming across the United States. It looks as if your best bets are to head to either Maine or Montana. Maybe DC, it’s too small to tell, but I kind of doubt that.

As you all know, I am a fan of small multiples and so I love this kind of work. To play Devil’s advocate, however, I wonder if an interactive piece that featured one large map could have worked better? Could the ability to select the week and then the state yield information on how the flu has spread across each state? I am always curious what other other forms and options were under consideration before they chose this path.

Credit for the piece goes to the FiveThirtyEight graphics department.