Make Way for Makemake

In case you hadn't noticed, there's been a lot of chaos in the outer solar system — not because distant objects are careening out of control, but rather because astronomers are struggling as they come to grips with how to characterize them.

Pluto and Makemake
The newly named Makemake is roughly two-thirds the size of Pluto. Click on the image to see how these compare with other large trans-Neptunian objects — and with Earth.
NASA / ESA / A. Feild (STScI)
Lost in the din over finding large, distant Eris and the subsequent debate over Pluto's planethood was the 2005 discovery of a Kuiper Belt object initially designated 2005 FY9 and later numbered as 136472. Quite bright (magnitude 16.7) despite its distance, 2005 FY9 turns out to be the third largest trans-Neptunian object (after Eris and Pluto); its diameter is roughly 950 miles (1,500 km). Curiously, 136472 is the only big Kuiper Belt object lacking a satellite.

These temporary designations can be so confusing. And then there's the nickname "Easterbunny," coined by the discoverers (Michael Brown, Chad Trujillo, and David Rabinowitz) because they'd found 2005 FY9 on March 31st, near Easter.

Finally, we can all start using this iceball's final, permanent, official name. On July 14th, the U.S. Geological Survey announced that it'll be called Makemake (pronounced MAH-keh MAH-keh). The International Astronomical union followed up with a press release on July 17th.

Objects in the Kuiper Belt are named for creation deities, and the god Makemake is the creator of humanity and the god of fertility for inhabitants of the Pacific island Rapa Nui. Most of us know this place as Easter Island — and the link to Easterbunny isn't a total coincidence. Mike Brown describes how his team and the International Astronomical Union came to agreement on Makemake in his online blog.

Now only one Kuiper Belt "giant," 2003 EL61, lacks a permanent name. It's big (1,200 miles long), has two moons, and has been numbered by the IAU (136108). But it might not get a name anytime soon — because there's disagreement about who discovered it.

5 thoughts on “Make Way for Makemake

  1. Michael C. Emmert

    Dear Sirs;

    We welcome Makemake into the family of named, discoved objects. The name kind of grows on you. It’s certainly better than some kind of license plate number.

    2003 EL61 appears to have been involved in a hit and run collision. So the question arises, what did it hit?

    I would nominate as a candidate Neptune’s strange, backwards orbiting moon Triton. I have simulated flybys of binary objects past Neptune and find that one common result is for the two object to collide. I would therefore suggest the name, Rhode, for 2003 EL61. She is the sister of Triton and mother or the Telechines. Plus, the name is open.

  2. Glenn Leider

    Concerning newly-named Makemake, the article states: “a Kuiper Belt object initially designated 2005 FY9… turns out to be the third largest trans-Neptunian object [or TNO] (after Eris and Pluto); its diameter is roughly 950 miles (1,500 km).” However, what of the ‘Kuiper Belt “giant,” 2003 EL61… (1,200 miles [c. 1,925 km] long)’? First of all, by definition it is also a TNO. Next, unless this is shaped like an oblong potato, shouldn’t it be ranked third? Last I checked, 950 < 1,200. At the very least, the article should explain why these objects are so ranked.
    Glenn: 2003 EL61 is very elongated, about twice as long as it is at its narrowest. So its mean diameter is only about 850 miles (1,350 km), as determined by Spitzer observations. — Kelly Beatty

  3. Michael C. Emmert

    Hi, Gleen 🙂

    I think the releative sizes of the two objects are beyond the scope of this article. Makemake appears to be larger, but it’s siae is poorly known. There is a very good mass estimate for 2003 EL61, about 28% the mass of Pluto, but there is evidence from it’s rapid rotation that it must be made out of stone to survive centrifugal force. It’s likely more massive than Makemake is spite of smaller volume.

    These fascinating objects leave much to be discovered.

  4. Mizar

    In the second paragraph of this article you state the diameter of Makemake in miles and then in kilometer. Later in the last paragraph you state the approximate size of 2003EL61 in miles alone and force the reader to pull out their calculators to find what that is in kilometer. Why did you do that? At the very least it is internally inconsistent. But maybe there is another reason.

    I have noticed the growing use of miles and Fahrenheit degrees (to name a few) creeping into your articles in recent years. I’m sure I’m not the only reader who would appreciate an explanation of Sky & Telescope’s policy regarding the inclusion of non-scientific units in the articles they publish.


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