Gravitationally Unbound: Interstellar Interloper ʻOumuamua

So I'm pretty late to write about this and you may have already heard about it by now, but in case you haven't, on October 19th the Pan-STARRS telescope in Hawaii discovered the first known object in our solar system that's unquestionably of extrasolar origin. The tiny interstellar wanderer, now known as 1I/2017 ʻOumuamua, was caught forty days after its closest approach to the Sun, and it was quickly realized that its speed—both on approach to and away from the Sun—was far too high for it to be gravitationally bound to the solar system.

This was pretty exciting, as this is the first time we've discovered an asteroid in our solar system that definitely came from outside it. There's been an intermittent stream of papers on ʻOumuamua over the weeks that followed its discovery, speculating on its possible origin, trying to figure out whether it's a comet or an asteroid (the latter seems most likely, given its complete lack of visible coma even after passing within the orbit of Mercury), even calculations on how far the Earth−Moon system would have moved if it were a macroscopic chunk of nuclear-density dark matter! (About ten meters/thirty-three feet was the conclusion, so don't worry about it.)

One of weirdest things about ʻOumuamua so far is its shape. Now, like all known asteroids it's much too small to make out its shape directly (even passing less than a fifth of the distance to the Sun from Earth). However, we can measure how its brightness changes over time (called its light-curve) which can tell us both how fast it rotates and how elongated it is…and that's the strange part. According to the large difference between the maxima and minima of its light-curve, ʻOumuamua must have a length ratio of something like 1:6 or even 1:10. Think cigar-shaped and you've got an idea of what it must look like. This is, needless to say, really, really odd, as nothing we know of in our solar system has a shape approaching anywhere near that ratio. Whatever it's made of must be holding itself together with more than just gravity.

Finally, if you're familiar with my blog, you've probably already guessed that the name ʻOumuamua is of Hawaiian origin. (And if you did, good job!) ʻOu means “to reach for,” while mua has several meanings but is generally associated with the idea of being first, foremost, leader, or senior. “I mua!” means “Forward!”, and ʻoumuamua (with some of that Hawaiian reduplication I've talked about) means scout (in a military sense), one sent on ahead or before. Which is the intended meaning of the name in this case, as ʻOumuamua will likely be only the first of more interstellar objects that we'll detect in the future.

Interesting times we live in! A hui hou!

An Australian Mountain Adventure

This Saturday I was invited on a sight-seeing trip to the Dandenongs (a mountain range just to the east of Melbourne) by a family from the church I've been attending, an opportunity I gladly jumped at.

Not the greatest picture as it was taken through the window of the car, but it gets the message across.

We stopped at a few places along the way up the delightfully winding road up the mountains, including a small town with a candy store (sorry, a “lollies shop”) where I picked up a small collection of sweets to try (purely in the spirit of sampling the local culture, of course!). Another place where we stopped for afternoon tea (read: snacks) had a large flock of cockatoos hanging around, plus a few other native birds.

These birds were quite used to being fed, and not shy about hanging around in hopes of food.

…to the point of happily jumping up on the picnic table in front of me!

It was really cool and a bit strange seeing flocks of birds flitting betwixt and sitting in the eucalyptus trees, as we didn't really have many birds that did that back in California, the only ones being the vultures that liked to nest in one particular large dead tree (and didn't do a lot of flitting among the branches, for obvious reasons).

This crimson rosella was perfectly fine walking underneath my seat, making it a little hard to photograph!

In fact, the cockatoos were comfortable enough with people to jump up your shoulder in search of food!

After our tea-time adventure, we hiked to Sherbrooke Falls in the Sherbrooke Forest National Park. On the whole, it reminded me of hiking amongst the redwoods back in California, except with eucalyptus trees instead. And what eucalyptus trees they were! I'd known that certain species of eucalyptus trees are among the tallest trees in the world (behind only redwoods), and having grown up among eucalyptus trees in California I thought I was familiar with their heights, but these trees were something else entirely. It's hard to guess of course, but I felt like many of the trees I saw had to have been at least twice as tall as the tallest eucalyptus trees I'd know previously, again underscoring the similarity to hiking in the redwood forests.

It's hard to tell and I could't get it all in one shot, but this is a tall tree.

The hike to the waterfall was quite pleasant, but the return journey was an adventure. It was a nice day when we set out, but as we started back the sky became cloudy and overcast. Soon we could hear thunder rumbling in the distance, then the tops of the trees were buffeted by an increasingly strong wind. By the time we'd gotten back to the carpark the first few large drops were falling, only for us to realize that we'd returned to the wrong carpark, having taken a wrong turn at one of the several branches in the trail on the way back.

As we regrouped to the map at the trail head and figured out where we were, the rain started coming down in earnest, followed soon after by hail! Luckily there were some other people leaving from the carpark due to the rain so our driver was able to get a ride back to the car and come back to pick us up where we were huddled beneath the increasingly-inadequate shelter of the tiny structure protecting the map as rain and hail pelted the ground around.

Thankfully we made it back through the hail and storm all right (though it was coming down fast enough to have significant water on the road in places), but it certainly made for quite the adventure! A hui hou!

Sir William Herschel: Accomplished Astronomer, Secret…Composer?

About five years ago, way back in 2012, I wrote a post describing how I had learned that Sir William Herschel, famous astronomer and discoverer of Uranus, was actually an accomplished classical musician and composer prior to becoming interested in astronomy. Looking back at that post, I realize I never bothered actually linking the album I'd found of some of Herschel's symphonies, so here's a link to that.

At the time, there wasn't a lot of Herschel's music available as recordings. Five years later, that's…actually still pretty much the case. Amazon has one CD with two random Herschel works (along with some Haydn for some reason?), plus a new CD in French that appears to be some of Herschel's organ works. I'm mostly guessing on that one, and it doesn't have a digital preview to check.

However! Over on Google Play Music, I came across a new album of Herschel's music that came out in 2015 when I searched his name there on a whim. It's a collection of six sonatas for harpsichord and violin, and it is fantastic. I've fallen in love with Herschel-as-composer all over again, and it makes me really wish more of his music was available, because seriously, this stuff is really really good.

You might be tempted to think that having only a harpsichord (one of my favorite instruments, by the way) and a violin would be a little limiting in what music you can make (Edit: on further listening, I'm pretty sure there's a cello in there too). Nope! Herschel manages to make each movement in each sonata completely unique, different and compelling, with some really interesting little musical motifs. I'm also not generally as big a fan of slow movements as I am of fast ones, yet he somehow made the Andante middle movement of the fourth sonata one of my favorite of the bunch!

All in all it's a really wonderful bit of music and I'd definitely urge you all to go have a listen. A hui hou!

Australian Creepy-Crawlies of the Redback Variety

So I've finally had a chance to see some of the things I shouldn't touch while in Australia! I went out for lunch on Sunday with a family from church, and after lunch as we were touring the yard they mentioned having noticed a redback spider a few days ago and and eagerly took me to see it where I managed to get a picture of a male and female pair (though they don't normally spend time this close together, that's an artifact of us disturbing them).

The large one on the right is a female, the smaller one is a male. Note the distinctive red stripe.

Redback spiders are in the genus Latrodectus, the widow spiders, to which the black widows I grew up with in California also belong. As such, they show very similar behavior, weaving stringy, chaotic-looking webs and being ambush predators, not being very aggressive, and generally only coming into contact with humans by accident. From what I've read their bites (of the females, specifically), although very painful, are hardly ever fatal. So that's reassuring, I guess. A hui hou!