A new look at the dwarf planet Makemake, one of the more recent additions to the known solar system, has pinned down some of the object's most basic—and important—attributes.

Astronomers took to observatories across South America in April 2011 to catch a rare glimpse of the dwarf planet—or at least its shadow—as Makemake (pronounced "mah-kee mah-kee") crossed in front of a faint background star and dimmed the star for about a minute. The duration of the occultation, as such celestial conjunctions are called, allowed the astronomers to more precisely estimate Makemake's physical size. The researchers reported their findings in the November 22 issue of Nature. (Scientific American is part of Nature Publishing Group.)

Perhaps more important than the new size measurement are the implications for a Makemakean atmosphere. The astronomers detected a sudden drop in starlight when Makemake’s occultation began, as if someone had suddenly switched the star to a lower wattage rather than dialing down a stellar dimmer switch. The sharpness of the occultation suggested that the dwarf planet lacks a significant global atmosphere, which would lend a fuzzy edge to its shadow. "If the decrease is abrupt, you see that there is not an atmosphere," says study co-author Noemi Pinilla-Alonso, a postdoctoral planetary scientist at the University of Tennessee Knoxville. By contrast, when Pluto passes in front of a star, "the decrease is gradual, which shows that there is an atmosphere."

Makemake, discovered in 2005, is one of five recognized dwarf planets, along with Ceres, Eris, Haumea and Pluto. Currently Makemake is near aphelion, the point farthest from the sun along its 307-year orbit in the Kuiper belt, a ring of comets and other icy objects beyond Neptune. Makemake's distance from the sun is presently more than 50 times that of Earth, placing the dwarf planet in an intermediate regime between the locations of Pluto and the more distant Eris. Whereas Pluto hosts a significant atmosphere, Eris's atmosphere appears to have frozen out and collapsed into a reflective surface layer.

Makemake may exist in an intermediate state, with only localized clouds of methane vaporized from the dwarf planet's sunward-facing side. "It doesn't have a global atmosphere, but it could have some local atmosphere," Pinilla-Alonso says. The researchers suspect that Eris, Pluto and Makemake all cycle through stages—from localized clouds to full-fledged atmosphere to atmospheric collapse—as the worlds move closer to, and then farther from, the sun.

Makemake does have methane frost on its surface, which should provide a ready supply of gas at the dwarf planet's warmer locales. "It absolutely has an atmosphere," says astronomer Mike Brown of the California Institute of Technology, who discovered Makemake in 2005, along with Chad Trujillo of Gemini Observatory in Hawaii and David Rabinowitz of Yale University. "It’s just a question of how much."

Makemake is only the latest of the dwarf planets to be carefully measured during an occultation. When Eris eclipsed a background star in 2010, astronomers found it to be a near-twin to Pluto in size (both are somewhat larger than Makemake). But opportunities to make detailed observations of Makemake during an occultation are few and far between. The dwarf planet passes in front of three or so background stars per year, but often the shadow from the occultation falls on a sunlit or cloudy part of Earth, or on a remote region without telescopes. The April 2011 occultation, which had been predicted the year before, cut right across South America, exposing Makemake to view from some of the world's premier observatories, including two European Southern Observatory facilities in Chile: the Very Large Telescope atop Cerro Paranal and the New Technology Telescope at La Silla in the Atacama Desert. According to José Luis Ortiz of the Institute of Astrophysics of Andalusia in Spain, lead author of the new study, such opportunities arise only about once a decade. In all, the astronomers witnessed Makemake's occultation from seven telescopes across South America, which allowed for an unprecedentedly precise estimate of the object's diameter.

6 Comments

1. 1. littleredtop 03:57 PM 11/21/12

   What good is all of this knowledge and speculation if we aren't going there? If Earth's civilized population doesn't get serious about space travel pretty soon it may be too late. In light of current world-wide political and economic issues, now might be the best time to depart this cesspool.

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2. 2. tharriss 06:05 PM 11/21/12

   Well, consider that there were thousands of years of human history where a grandchild's life would pretty much be exactly like his grandparent's life was, and now we are in situation where kids are experiencing totally different levels of technology than their parents did, and the pace is increasing pretty rapidly.
   
   While it might not be happening in the order or pace we might like for some things like space travel, massive technological/scientific change is coming, and coming fast.
   
   What seems like "we aren't going there" to you now, will probably be "hoh hum, been there, done that" to our kids.

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3. 3. paulsophie1 in reply to littleredtop 06:56 PM 11/21/12

   Or we can always move to Russia
   http://bit.ly/RV0F1s

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4. 4. neilrued in reply to littleredtop 01:42 AM 11/22/12

   Google orbital mechanics related to Makemake, Eris and Humea.
   
   Take a look at:
   http://en.wikipedia.org/wiki/New_Horizons
   
   Pluto and its three known moons are closer than Makemake, Eris and Humea. New Horizons was launched in 2009 and won't fly-by past Pluto until 2015.
   
   I would not expect Makemake, Eris or Humea to be within maneuvering range of these dwarf planets.
   
   NASA was lucky Congress approved funding for New Horizons. Makemake, Eris or Humea may not be explored within our lifetimes because Congress is looking at slashing NASA's shoe string budget further.
   
   Running away doesn't solve any problems. The rich caused the current Global Financial Crisis due to their unbridled greed, so it's their responsibility to fix it.

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5. 5. pabelmont 05:57 PM 11/24/12

   littleredtop : What is this concern for space travel all about anyhow? Should the human race (or its scientists) stop worrying about global warming (and the likely end of things as we know them) is favor of the craziness of looking into space travel (so as to establish "civilization" on some innocent planet and to escape from the hell we so industriously produced here on earth?
   
   Why SHOULD human life or much of Earth's terrestrial life be preserved (if that's what would happen) on another and very different planet, supposing the energy (etc) needed for all that space travel? Why should even a Noah's Ark sort of space travel be organized? for what benefit, and to whom?
   
   Better for us all to get VERY BUSY with trying to reap a different crop from what we've (environmentally) sown.

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6. 6. littleredtop in reply to pabelmont 01:26 PM 11/25/12

   Global warming is a natural occurrence that has been going on since the end of the last ice age and the process will only end when Earth's temperature returns to an appropriate level. The political and scientific movement called "Global Warming" is only a "smoke and mirrors" initiative to take your money.

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