Pay $5 to nominate an exoplanet name?

I guess it’s not surprising that someone would find a way to monetize the exoplanet craze. A startup named Uwingu will now charge you $4.99 for the chance to nominate a name for an exoplanet (plus a downloadable certificate). Not a specific exoplanet, mind you. No, they’re simply compiling “a baby book of names” for astronomers to consult, should they choose to.

That’s right, there’s no guarantee that your suggestion will ever be used, and since it’s not associated with any particular planet, no chance for you to make it suit the planet’s characteristics. (That makes the baby-name analogy more apt, actually, since most parents choose names before the child is born.)

But if so, why should Uwingu get to collect $4.99 for it? And what will they do with the funds?

“Our goal is to award up to half of all Uwingu’s proceeds to The Uwingu Fund, which will provide grants to scientists and educators to conduct space research, education and exploration projects,” says Uwingu. Their first call for grant applications will happen in mid-2013.

But wait, there’s more!

You can pay them $0.99 to cast a vote for the best name, a contest that closes on April 22. Just $0.99 for each vote! What happens to the winning name? They want to assign it to Alpha Centauri Bb, but since they have no authority over official naming, nothing will actually happen. It would be like a band of people deciding to rename New York to be “The Big Apple.” Sure, you can use the name colloquially, but no one’s going to start changing road signs or the name over City Hall or birth records.

So far they’ve received 1230 nominations and 4933 votes, or $11,021. The most popular name is currently Rakhat.

The International Astronomical Union (IAU), which oversees the offical naming of astronomical bodies, is apparently not on board with this at all.

“Such certificates are misleading, as these campaigns have no bearing on the official naming process — they will not lead to an officially-recognised exoplanet name, despite the price paid or the number of votes accrued.”

Uwingu CEO Dr. Alan Stern stated, “This is a first step in democratizing planet naming.” . . . which should be democratic why?

Far be it from me to dissuade any popularizing of science and astronomy. But this seems overly opportunistic, reminiscent of those “Name a Star” scams (check out some words of wisdom from the IAU). It would be one thing if they were compiling a list of names as the outreach-based, public awareness effort they claim it is. But the charges they levy instead highlight it as a semi-deceptive money-making venture, playing on people’s desire to be involved but not delivering what most people think they’re paying for.

Solstice drift, and how to fix it

The summer and winter solstices happen around the 20th of June and December, respectively. Around the 20th? That seems rather… imprecise, for an astronomical event with a precise definition: the time at which the Sun reaches its “highest or lowest excursion relative to the celestial equator on the celestial sphere” or, for the viewer standing on the Earth, its highest or lowest altitude from the horizon. This is determined by the Earth’s orbit and corresponds to the time at which your current hemisphere’s pole points most closely to, or farthest from, the Sun. So why doesn’t it happen at the same time each year?

Inspired by an awesome book I recently acquired (“Engaging in Astronomical Inquiry” by Slater, Slater, and Lyons), I decided to investigate. I used the Heavens Above site to pull up historical data for the summer and winter solstices going back to 1980. I plotted the time for each solstice (in Pacific time) as its offset from some nearby day (June 20 or December 21). And sure enough, here’s what you get:

The solstice time gets later by about 6 hours each year, until a leap year, when it resets back by 24 – 6 = 18 hours.

Of course, the solstice isn’t really changing. The apparent change is caused by the mismatch between our calendar, which is counted in days (rotations of the Earth), and our orbit, which is counted in revolutions around the Sun. If each rotation took 1/365th of a revolution, we’d be fine, and no leap years would be needed. But since we’re actually about 6 hours short, every 4 years we need to catch up by a full rotation (day).

Now, we all know about leap years and leap days. But this is the first time I’ve seen it exhibited in this way.

Further, you can also see a gradual downward trend, which is due to the fact that it isn’t *exactly* 6 hours off each year. It’s a little less than that: 5 hours, 48 minutes, and 46 seconds. So a full day’s correction every four years is a little too much. That’s why, typically, every 100 years we fail to add a leap day (e.g., 1700, 1800, 1900). 11.25 minutes per year * 100 years = 1125 minutes, and there are 1440 minutes in a day. But that’s not a perfect match either… which is why every 400 years, we DO have a leap day anyway, as we did in the year 2000.

This is what, in computer science, we call a hack.

And now it is evident why for every other planet, we measure local planet time in terms of solar longitude (or Ls). This is the fraction of the planet’s orbit around the Sun, and it varies from 0o to 360o. It’s not dependent on how quickly the planet rotates. It’s still useful to know how long a planet’s day is, but this way you don’t have to go through awkward gyrations if the year is not an integral multiple of the day.

By the way, you can get a free PDF version of ‘Engaging in Astronomical Inquiry’. If you try it out, I’d love to hear what you think!

Detecting exocomets around other stars

We’ve heard many discoveries over the past decade of planets around other stars. Today astronomers announced the detection of seven new comets around other stars. You can read more here: “Exocomets may be as common as exoplanets”.

Why should we care? Well, comets are a lot smaller than planets, so it’s impressive that they can be detected at all. Even more impressive, these discoveries were made with a 2.1-m telescope on the ground, not in space. You might be wondering how exactly they were detected if it’s so hard even to find Earth-sized planets. That’s because these comets aren’t being detected directly, e.g., by the brief drop in stellar brightness when a planet transits in front of it. Instead, what’s actually being detected are slight perturbations (lasting about 5 days) to the star’s spectrum across multiple wavelengths, which indicates a compositional difference. Since we don’t expect the star to briefly change its composition and then revert back, this is interpreted as seeing gases boiling off the comet as it passes close to the sun.

If so, I’d expect that the particular changes would serve as a kind of “fingerprint” for that particular comet, and be somewhat repeatable the next time it approaches its star. But comet periods can be a lot longer than planet periods (at least in our solar system) so it might take a while to get any repeat signals.

The scientific reason this is interesting is that it can serve to fill in a gap in our knowledge. We’ve seen systems with dusty disks surrounding the star (before planets form), and we’ve seen more mature systems with their planets already formed. We haven’t yet explored the in-between stage in which a lot of material (comets, asteroids) is moving around in the process of forming into large planetesimals. For that reason, astronomers targeted young (type A) stars for the exocomet hunt.

Further, turns out that the technique used wouldn’t work with older/cooler stars. In discoverer Barry Welsh’s talk today at the AAS meeting (he’s giving a press conference tomorrow), he noted that the spectral absorption features they think come from comet outgassing get “narrower and harder to detect in older stars.” I’m not sure of the specifics on this, but it suggests we won’t be able to find exocomets in all of the stars we’ve been studying… at least this way. Astronomers’ innovations will continue to push the envelope!

See our Earth transit, too!

Perhaps you saw the recent Venus transit of the Sun. But what about an Earth transit?

Obviously we can’t see such a phenomenon while sitting on the Earth itself. But some clever astronomers have done calculations to work out when the Earth would transit the Sun from the perspective of other bodies in the solar system, including the Moon and Jupiter.

“In January 2014, Jupiter will witness a transit of Earth. And we can see it too, the astronomers say, by training NASA’s Hubble Space Telescope on the huge planet and studying the sunlight it reflects.”
(From NBCNews, June 4, 2012)

Using Jupiter as a mirror seems a curious strategy, since the reflected light will also be influenced by the chemical makeup of Jupiter’s atmosphere. However, just as with the hunt for exoplanets, if we can stare at Jupiter for long enough before the transit occurs, we can build a good enough model so its factors can be subtracted out from the Earth+Jupiter signal during the transit. Scientists first plan to test this strategy with a Venus transit that Jupiter will see (Earth won’t) in September of this year. And I’ve seen talk that they used the Moon as a mirror to observe the recent Venus transit from the Earth vicinity — but I haven’t been able to find any images of the result yet. Here’s how it works:

Hunting for exomoons

Finding planets? Old hat. What about finding moons?

It seems likely that planets around other stars might also be hosts to their own moons. In addition to just wanting to know what’s out there, detecting exomoons could have implications for the habitability of exoplanets. While gas giants themselves might not be habitable, their potential rocky moons could be, if the planet orbits in the habitable zone. Also, moons can help stabilize a planet’s orbital inclination over long time periods, making it easier for life to maintain its hold rather than experiencing dramatic oscillations in environmental conditions.

This video shows the expected effect that a moon could have on the light curves we observe remotely:

The Hunt for Exomoons – Lightcurve Demo from Alex Parker on Vimeo.

The effect here is quite noticeable because the moon is at high inclination (out of the plane of the planet’s rotation around its star).

HEK (the Hunt for Exomoons with Kepler) is a collaboration established with hopes of finding the first exomoon in Kepler data. They were successful in getting some crowdfunding from PetriDish.org to purchase a supercomputer for their search. Laudably, they plan to post numeric posterior results from their search as an aid to the community.

Exomoons are theorized to tweak the planet’s transit curve in a variety of ways, but they are subtle and in many cases can be confused with other causes (like interactions with other planets in the same system). The community is still working to develop reliable models.

So, no exomoons have yet been found — but it’s probably just a matter of time.

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