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.

It’s Finally Sunny in Philadelphia (on the Weekend)

Here in Philadelphia, the weekend is forecast to be not rainy, which is a departure from the last several weeks. So this piece from xkcd’s Randall Munroe seemed appropriate.

That gap is also something like 150 million kilometres away
That gap is also something like 150 million kilometres away

Credit for the piece goes to Randall Munroe.

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.

The Timeline of the Voyager Mission

There are a bunch of things to look at this week, but what am I most excited about? Voyager. No, not Star Trek. (Did you know that the Vger entity from the first Star Trek film was a replica of the Voyager probes?) I am of course talking about the Voyager mission to the outer Solar System and beyond.

40 years ago today Voyager 1 lifted off from Cape Canaveral—Voyager 2 left two weeks earlier, but would reach Jupiter and Saturn after Voyager 1, hence being named 2—and it has been collecting images and data for science ever since.

On 25 August 2012, Voyager 1 emerged from the heliosheath and entered interstellar space. In other words, Voyager 1—and sometime in the next few years perhaps—is the first manmade spacecraft to ever leave the Solar System. Mankind is finally out there among the stars.

I love space things.

So JPL and NASA put together this interactive timeline of the mission, which of course continues tomorrow and for years after today until their nuclear fuel runs out.

Boldly going…
Boldly going…

Credit for the piece goes to JPL and NASA.

The Solar Eclipse as Seen from Philly

As my last two posts pointed out, yesterday was the Solar Eclipse. It certainly garnered media attention as a news helicopter hovered over my building during the height of the eclipse. Very peaceful indeed. But, knowing that my smartphone would not be able to take the best photos of the eclipse, even with a solar filter, I decided to do what any good designer might do. I sketched out the eclipse.

The task of sketching an eclipse is not easy. You cannot, or at least should not, look directly at the sun. (You’ll burn your eyes out, kid.) But the solar filters make seeing anything but the most intense light sources near impossible and so you have to remove them in order to doodle in a sketchbook. Eventually I found a solution and was able to quickly move from filtered glimpses of the Sun to the sketchbook. (At least when the clouds would permit.)

Last night I digitised those sketches into this simple graphic. The sketches are not entirely accurate as the position of the Moon jumps in a few spots. But it does give you the impression of peak eclipse about 14.45 with just a sliver, or 25% of the Sun remaining visible. And indeed the neighbourhood was visibly darker.

The colour may be too yellow, but since I only saw it through a filter, I cannot say what the exact colour of the Sun was
The colour may be too yellow, but since I only saw it through a filter, I cannot say what the exact colour of the Sun was

Solar Eclipse Day

Today is Solar Eclipse Day.

Thankfully Vox has put together a great interactive piece to help you plan your day. This is for my viewing area in Philadelphia. We only max out at 75% of the sun, but that is still pretty fantastic.

I'm totally excited for this
I’m totally excited for this

Credit for the piece goes to Casey Miller, Ryan Mark, and Brian Resnick.

The Solar Eclipse

If you have not heard, the entire continental United States will, weather cooperating, be able to see at least a partial solar eclipse on Monday, 21 August. It is still too far away for an accurate weather forecast, but I am hoping that we have good weather in Philadelphia that day. Or else why bother working from home that day?

In the meantime, enjoy this eclipse-related piece from xkcd that ties together my love for astronomy things with my love for political things.

This weekend will be crazy town
This weekend will be crazy town

Credit for the piece goes to Randall Munroe.

New Neighbours

Among the many, many stories that broke during my month-long radio silence, I got fairly excited about the discovery of a planet orbiting Proxima Centauri. And not just any planet, but a likely rocky planet within the star’s habitable zone. Put that all together and there is the possibility that the planet could host life as we know it. How can that not be exciting? Thankfully the Guardian put together a graphic to support an article detailing the discovery.

Our newest neighbour
Our newest neighbour

Credit for the piece goes to the Guardian’s graphics department.