Why, King Triton, how nice to see you!

By Phil Plait | March 13, 2009 2:31 pm

It figures: I spend hours and hours putting together my Ten Things post about Pluto, and the New Horizons team releases a way cool image too late for me to include it!

But it is way cool. Check this out:

Neptune and Triton as seen by New Horizons

This image shows Neptune and its large moon Triton. That’s a remarkable shot, given that the planet and moon were nearly four billion kilometers away when it was taken!

As I mentioned in the Pluto post, Neptune and Pluto never get really close together, so New Horizons isn’t exactly dropping by on its way to Pluto. This image was taken as a test of the equipment, and has some scientific value as Emily points out. And as the press release says:

Triton is only slightly larger than Pluto (1,700 miles [2,700 kilometers] in diameter compared to Pluto’s 1,500 miles [2,400 kilometers]). Both objects have atmospheres primarily composed of nitrogen gas with a surface pressure only 1/70,000th of Earth’s, and comparably cold surface temperatures (-390° F on Triton and -370° F on Pluto). Triton is widely believed to have once been a member of the Kuiper Belt (as Pluto still is) that was captured into orbit around Neptune, probably during a collision early in the solar system’s history.

New Horizons will start taking images of Pluto while it’s still a long way off from the tiny world, so this observations shows the probe is up to the task.

In case you’re curious, the image itself is interesting. Neptune was overexposed, causing that column of light called blooming. This kind of detector "sees" light by converting incoming photons into electrons, and then counting the electrons. But if an object is too bright, too many electrons are created which overflow the pixels, something like rain overflowing a bucket. Due to the structure of the detector, the electrons flow more easily in one direction than another, and you get blooming. Worse, this effect can suppress the number of electrons seen per pixel along that column, which is why there is a dark streak above Neptune as well.

This kind of thing is just something you have to deal with when using electronic detectors of this type. It takes a while to get used to it, and can lead to all sorts of problems (there could be a faint interesting source near your target that gets obliterated by this effect). It also leads to pseudoscience, as I pointed out in my Planet X debunking a while back.

In science you have to understand your camera just as well as your astronomical target. Clearly, the astronomers involved with New Horizons did for their detector, since you’ll note that Triton is off to the side, away from the blooming issue.

And for those wondering about the post title… it’s from The Little Mermaid. Ursula said it, and I used to imitate her to crack up The Little Astronomer when she was very little. It still makes me laugh.

CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (15)


    Phil Plait:

    It figures: I spend hours and hours putting together my Ten Things post about Pluto…

    Well, that explains why you posted that article at 4:00 a.m.!

  2. Very nice. Thank you for this photo, and for so many other interesting articles. I’ve always had only a peripheral interest in astronomy, but I have learned a lot since I started reading your blog :-)

    ps. I immediately recognized the quote from the title – the advantages of having a young daughter. Ursula is my favorite character of that movie!

  3. Great read, although the thought of you imitating Ursula… *shudders* At least I hope you didn’t go for the blue eyeshadow! (I did recognize the quote right off, my little scientist is 12.)

  4. In reality, those 10 Things posts take several days to put together, and are a lot of work. Just finding the images and getting permissions (if needed) can take many hours. In this case, I finished the Pluto one Thursday and set it up to post automatically at that time, so people in the UK and Europe would see it before the day was over. :)

    Ironically, I wrote this Triton post at 4:00 a.m. Dog scratching at the door woke me up, and I figured why waste the insomnia that ensued?


    Well, both posts excellent as always, Phil. However, “-390° F on Triton and -370° F on Pluto”?! :roll:

    For us metric orientated individuals, that’s:

    -234.44 °C (38.7 K) on Triton and -223.33 °C (49.82 K) on Pluto.

  6. MadScientist

    So Neptune is only a few arc seconds across as seen by New Horizons? I wonder if they simply took a shot or if the telescope was being stabilized in any way; you can see stars (and Triton) smudged.

    I hope everything goes well for them; that’s an awfully long wait to finally collect the data you want. Are they working on a follow-up yet? I want to see a Plutonian orbiter!

    Now going back to planets and stuff – I suggest we drop the name ‘planet’ altogether. After all the original planets were allegedly called that because they wandered in relation to the other ‘fixed’ stars. Since we never saw the earth as a bright dot wandering among the stars, we should never have called the earth a planet. I’d suggest the name “non-stellar orbiting body” instead. That’s just my own contribution to setting back astronomy by a few decades.

  7. Buzz Parsec

    How about “stellar (non) orbiting body” instead, since whether something is a planet or not is purely a matter of SNOB appeal? (Are snob zoning and and anti-snob zoning laws purely a Massachusetts thing or do other people know what that’s all about? Many of the wealthier suburbs around Boston had/have minimum lot sizes of an acre or more. Anti-snob zoning laws are attempts by the more densely populated cities to counteract this. Since land is expensive around here, the zoning rules kept out the riff-raff and undesirables. Such as Pluto …)

  8. Michelle

    It’s great to hear back from New Horizons. This is a mission I been dreaming of since I was a little kid. I know nowadays Pluto isn’t a planet anymore (And I’m pretty sure a big chunk of rock and ice doesn’t care what we call it) but as a kid it was the only planet we didn’t have cool hi-res pictures of. I want to see it SO BAD now. When the day comes I’ll be DROOLING all over that.

    So far awayyyy still… Agh.

  9. I will second IVAN3MAN there: wouldn’t it be nice to stick to the metric system in science blogs?

  10. Alan Stern

    Of course, it is a planet, 2500 kilometers across, with an atmosphere, moons, geology, seasons, polar caps, and a core.

  11. Elmar_M

    I am kinda suprised that this detector is producing artefacts like that. I know the effect and how it happens. There is simillar things that can happen in radiology, particularily CT scans. The thing is that a CT- scan is much more complex in the way it has to reconstruct the image. Yet even modern CT scanners have special filters and other methods to reduce this sort of artefacting.
    I would, e.g. assume that a multi detector system or an axially rotating detector together with some filter software should be able to deal with this sort of issue. This should be much easier than with a CT scan.
    It is somewhat surprising that in a multi million dollar space mission, noone bothered with fixing this issue.

  12. CoffeeCupContrails

    When you say that the scientists who designed the camera were aware of the issue, I believe you. But was the fact that Triton was off to the side mean that there were just lucky rather than actually than taking the blooming into account when they took this picture? Maybe they predicted which direction the blooming would be when New Horizon was where it is right now wrt Neptune and Triton, in which case that’s really smart. It shouldn’t be hard I guess.

    @Elmar_M: look up Harvard IIC’s Astronomical Medicine Project where they use medical imaging technology for astronomy. Here’s a press release:


  13. Elmar_M

    Yeah, I do actually develop software that allows to visualize data like that. So far I just never had access to a 3d grid of atronomical data. This is due this usually being not on a grid, but as individual particles. The only example I have seen so far was the Virgo Cluster. The problem is that that was in some cryptic format that noone really cares about.
    If you have access to 3d grid astronomical data, I would sure love to give it a shot with our software. It would definitely be a nice diversion from the medical images we usually deal with every day (and our software can do so much more!)

  14. Troy

    I recall in elementary school, before charged-coupled devices (CCDs) when photographic film was still being used, a similar effect in the image taken to show Neptune and its two moons known at the time Triton and Nereid. (The photograph I saw only had the blossom effect not the black and white pillar.) It is of course a remarkable image. While it has a practical use, it would be great if they took more images that took advantage of their unique perspective of space. Amid calibration checks and scientifically relevant shots why not a chance or two to smell the roses?


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