Science
Related: About this forumSurprise, Asteroid 1998 QE2 has a moon!
From Universe Today:
The radar images were taken were taken on May 29, 2013, when the asteroid was about 3.75 million miles (6 million kilometers) from Earth.
Radar really helps to pin down the orbit of an asteroid as well as the size of it, said Paul Chodas of NASAs Near-Earth Object Program office, speaking during a JPL webcast about this asteroid on May 30. We now know our size estimates were pretty good, but finding it was a binary was surprising.
NASA said that about 16 percent of asteroids are binary or even triple systems.
Radar images from May 29, 2012 of Asteroid 1998 QE2,
showing its binary companion. Credit: NASA.
Wow! I wonder if it's made of green cheese, just like Earth's moon???
The following is a sequence of radar images recorded by NASA's Deep Space Network antenna in Goldstone, Calif., showing the rotation of asteroid 1998 QE2 plus its moon, visible as a bright spot. Credit: NASA / JPL-Caltech / GSSR
CaliforniaPeggy
(150,058 posts)I'm amazed...
DreamGypsy
(2,252 posts)...and I have a moon. Not observed by a lot of people, I hope...my parents, my wife, I guess a bunch of guys in the showers after PE. I have no idea how it would appear to radar...?
But seriously, CA-Peggy, you have a good point.
I searched on "smallest moon" and found this, What is the smallest moon in the solar system?:
Jupiter's smallest moon is probably S/2003 J 12 or S/2003 J9 at only 1 kilometer in diameter.
Saturn's smallest moon is probably Aegaeon at only 0.5 kilometer in diameter - although it is classified as a moonlet.
If you don't want the moon to be around a planet, the Asteroid IDA (243 IDA) has a tiny moon called Dactyl which is under a kilometer in diameter.
So, Aegaeon wins as the smallest known moo(let), at 500 meters in diameter. The unnamed moon of Queen Elizabeth 1998 is apparently second.
CaliforniaPeggy
(150,058 posts)leveymg
(36,418 posts)Scroll down to the bottom of the post here: http://www2.ess.ucla.edu/~jlm/epo/planet/planet.html
Apparently it has sufficient mass to retain its own satellite, which is surprising. Both of them are soon to be visiting our part of the solar system.
The fact that it has a moon shows that 1998 that it has "cleared its neighborhood" of other objects, and is is a full-fledged planet, according to another IAU definition: http://en.wikipedia.org/wiki/Clearing_the_neighbourhood
In the end stages of planet formation, a planet will have "cleared the neighbourhood" of its own orbital zone, meaning it has become gravitationally dominant, and there are no other bodies of comparable size other than its own satellites or those otherwise under its gravitational influence. A large body which meets the other criteria for a planet but has not cleared its neighbourhood is classified as a dwarf planet. This includes Pluto, which shares its orbital neighbourhood with Kuiper belt objects such as the plutinos. The IAU's definition does not attach specific numbers or equations to this term, but all the planets have cleared their neighbourhoods to a much greater extent than any dwarf planet, or any candidate for dwarf planet.
The phrase may be derived from a paper presented to the general assembly of the IAU in 2000 by Alan Stern and Harold F. Levison. The authors used several similar phrases as they developed a theoretical basis for determining if an object orbiting a star is likely to "clear its neighboring region" of planetesimals, based on the object's mass and its orbital period.[2]
Clearly distinguishing "planets" from "dwarf planets" and other minor planets had become necessary because the IAU had adopted different rules for naming newly discovered major and minor planets, without establishing a basis for telling them apart. The naming process for Eris stalled after the announcement of its discovery in 2005, pending clarification of this first step.
This could change the way we view planetary systems, or that moon could just be an interstellar craft in a parking orbit.
DreamGypsy
(2,252 posts)Yes, it has a moon. But that's not enough. Wikipedia currently asserts that:
1998 QE2 is only 1.7 miles in diameter. It looks round-ish, from the radar images. But is it round enough to determine that it has assumed hydrostatic equilibrium? Do we know that it has cleared its neighborhood? Does its orbit avoid the orbits of all other more massive asteroids so it can assert gravitational dominance?
I'm awaiting the official word from the IAU.
leveymg
(36,418 posts)avoided the orbit of other more massive asteroids, it would itself be in orbit.
I'd argue it's a planet.
The fact that it appears to have a moon is extraordinary. Almost off the charts.
DreamGypsy
(2,252 posts)...but as QE's orbit changes due to occasional passes near earth, or other large bodies, will some future path bring her into close conjunction with Ceres? If so, who will win?
Only the computer analysis knows for sure.
Angleae
(4,518 posts)There's this little body of rock called Earth nearby. It needs to clear the complete solar orbit to meet the specifications, not just the immediate area.
leveymg
(36,418 posts)See, http://www.pbs.org/newshour/rundown/2011/07/trojan-asteroid-synced-in-orbit-with-earth.html
If 1989 QE2 were in planetary orbit, I'd agree with you. If it's not in orbit around another body other than the sun (that we've been able to determine), and has a satellite of its own, then how has QE2 not cleared its orbit?
Angleae
(4,518 posts)This is the reason Pluto isn't a planet any more. It hasn't cleared everything significantly larger that it from it's orbit, most notibly Neptune.
muriel_volestrangler
(101,502 posts)and neither is QE2. Its orbit crosses that of Mars and the asteroid belt. Not only does it have close encounters with Earth (<0.04 AU), it has them with Vesta too (<0.02 AU): http://echo.jpl.nasa.gov/asteroids/1998QE2/1998QE2_planning.html
Jackpine Radical
(45,274 posts)So, naturalists observe, a flea
Hath smaller fleas that on him prey;
And these have smaller still to bite 'em;
And so proceed ad infinitum.
DreamGypsy
(2,252 posts)...Tom Swifties.
"Who left the toilet seat down?" Tom asked peevishly.
"They had to amputate them both at the ankles," said Tom defeatedly.
While their exact origins remain uncertain, the spread of Tom Swifties in the United States was abetted by an article in the May 31, 1963 edition of TIME Magazine, which also announced a contest for its readers to submit their own Tom Swifties. Included was a special category, "TIME Swifties," which were to contain a reference to TIME Magazine;[2] however, only a few submissions were made of this nature. Among the submissions that were subsequently printed was "Someone has stolen my movie camera!" Tom bellowed and howled.
The TIME contest caused the popularity of Tom Swifties to grow, for a period of some years. Tom Swifties found a large teenage audience on the joke column on the last page of each month's issue of Boys' Life, the magazine for Boy Scouts.
There are two Tom Swifties that I remember well, because ... I think...I was the originator. Both are about toothpaste. Is that weird or what?
"Oh, I dropped my toothpaste" said Tom, crestfallen.
"Ahh!! My toothpaste tube exploded!!!" said Tom with a gleem in his eye.
DeSwiss
(27,137 posts)Unknown Beatle
(2,677 posts)Maybe that's a spaceship. Maybe that was what the Heaven's Gate cult was waiting for. Maybe they confused Asteroid 1998 QE2 for the Comet HaleBopp.
But, maybe not. Who knows what's in the minds of religious cultists.