Saturday, July 4, 2009
Carnival of Space #110 @ Kentucky Space
Check out the weird and wonderful Phobos Grunt, Liberty, and Pants on fire edition of the Carnival here at Kentucky Space.
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CarnivalOfSpace
Thursday, July 2, 2009
Pet Rocks? Naming things in Space
Have you ever wanted to get something in space named after someone? Well it turns out you can but it's not as easy as filling out a web form or paying some money.
Once you've found it you can pick almost anything your heart desires. There are a few naming rules (non-offensive, 16 or fewer characters, and reasonably distinct). You get your very own pet rock in space!
So ever wonder who asteroid discoverers are thinking about? If you are you can checkout this list at the Harvard University Minor Planet Centre. Here are a few examples of the kinds of people, places, and things honored by asteroid hunters:
Science-fiction and other authors:
Computers and Software
Satellites and things astronomical
Of future names
Because the pace of asteroid discovery has picked up in recent years there are so many now that many will never receive names. Discoverers may take the lead of Mike Brown who discovered Vanth (moon of Orcus) by opening up for suggestions.
Here are a few modest suggestion:
And if your confused there is a source for the meanings of asteroid names.
Finally, once you've named it or found one with a name that interests you, you can look up its orbit with the JPL Orbit Simulator. Just look up the name or number and go.
Related Articles:
- Lot's of people are interested in naming stars after someone (I regularly see queries from search engines for this). But, the truth is you can't really do it. There are lots of people who will take your money for a piece of paper. It will be for a star you'll likely never see and no one will recognize. If you really want to, use one of the free services mentioned in a related article and treat it as entertainment.
- If you discover a comet, they'll name it after you. And if you're a co-discoverer then you'll be hyphenated. In today's world there is a very good chance the other side of the hyphen is a robot telescope like LINEAR, Catalina, SOHO, or NEAT. With all the robots looking for stray rocks, the chances of double hyphenation (ouch) are pretty good.
- If you're good enough to discover a planet, dwarf planet, or moon then you get to submit the name. But to do this you're going to be a professional planet hunter. And if you do, the name will probably fit the current theme such as underworld deities. (And no, Kate Beckinsale does not count.)
- If you have a talk show you might be able to hijack a poll and get some space equipment, like a treadmill, named after you.
Once you've found it you can pick almost anything your heart desires. There are a few naming rules (non-offensive, 16 or fewer characters, and reasonably distinct). You get your very own pet rock in space!
So ever wonder who asteroid discoverers are thinking about? If you are you can checkout this list at the Harvard University Minor Planet Centre. Here are a few examples of the kinds of people, places, and things honored by asteroid hunters:
Science-fiction and other authors:
- Douglasadams (25924)
- Bradbury (9766)
- Clarke (4923 )
- Heinlein (6371)
- Hemingway (3656)
- Shakespeare (2985)
- Tolkien (2675)
- Jacquescousteau (6542)
- Einstein (2001)
- Fermat (12007)
- Fermi (8103)
- Hawking (7672)
- Heimlich (10637)
- Oppenheimer (67085)
- Szilard: (38442)
- Turing (10204)
- Johncleese (9618) - silly orbit no doubt
- Cronkite (6318)
- Bobbyfisher (19577)
- Flynn (2994)
- Gehrig (5891)
- Carygrant (9342)
- Hitchcock (7032)
- (Howard) Shem (30444) - of the 3 Stooges
- Kubrick (10221)
- Monroe (3768) - Marilyn
- Jesseowens (6758)
- Spassky (11268)
- Warhol (6701)
- Beatles (8749)
- Beethoven (1815)
- Enricocaruso(37573)
- Enya (6433)
- Pink Floyd (19367)
- Rolling Stones (19383)
- (Neil) Armstrong (6469)
- Annefrank (5535)
- Gagarin (1772)
- Grant (3154)
- Lee (3155)
- Lincoln (3153)
- Evita (1569)
- Tunguska (5471)
- Vesuvius (13897)
- Beowulf (38086)
- Enterprise (9777)
- Excalibur (9499)
- Nautilus (9769)
- Nemo (1640)
- Paris (3317) - of Troy
- Sherlock (5049)
- Mr. Spock (2309)
Computers and Software
- ASCII (3568)
- APL (132524)
- Fortran (9548)
- GNU (9965)
- Edmonton (96193)
Satellites and things astronomical
- Alouette (9995)
- Davidunlap (70207)
- (Helen) Sawyer Hogg (2917)
- (Ian) Shelton (5953) -who ran the DDO outreach program
- Toronto (2104)
Of future names
Because the pace of asteroid discovery has picked up in recent years there are so many now that many will never receive names. Discoverers may take the lead of Mike Brown who discovered Vanth (moon of Orcus) by opening up for suggestions.
Here are a few modest suggestion:
- Baden-Powell
- MarvintheMartian
- FlinFlon or Tarzana
- Timbuktu or TristanDaCunha
- TomLerher
- Kipling
And if your confused there is a source for the meanings of asteroid names.
Finally, once you've named it or found one with a name that interests you, you can look up its orbit with the JPL Orbit Simulator. Just look up the name or number and go.
Related Articles:
Labels:
Astronomy
Monday, June 29, 2009
Twisted Carnival of Space #109
Hop on over to the 109th Carnival of Space courtesy of Twisted Physics - where you can find out about spacey B-movies, staring into a really big black hole, Apollo's plan B, solsitice celebrations, more Tunguska, Canadian fusion, a shrinking planet, and more!
Enjoy.
Enjoy.
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CarnivalOfSpace
Sunday, June 28, 2009
Shrinking Mars will not appear as big as the full Moon
Every summer since 2003, emails make the rounds talking about how Mars will appear as big as the full Moon. This is complete nonsense.
I received my first Mars Hoax email of the season last week and thought I should clear the air.
In fact not only is Mars not going to be this big, in one sense it is shrinking ...

Origins of the Mars Hoax
On August 27, 2003 Mars and Earth lined up in what is known as an inferior conjunction or opposition. This is a normal astronomical event which happens every 26 months. That year the opposition was special because it was closer than normal. A lot was made of the fact that at 55.7 million km it was the closest Mars and Earth had come in almost 60,000 years.
A more realistic view is that Mars and Earth oppositions bring the two planets within the wide range of 55 to 101 million km. But they only get to close end of this range every 7 or 8 oppositions (e.g. 1956, 1971, 1988, 2003, 2018, 2035, 2050). When Mars is in close opposition it is nearly twice as close and will appear nearly twice as big. During these close oppositions Mars will appear much brighter than normal but you will still need a telescope to see it. These close oppositions are the very best times to see Mars through a telescope. The neighbouring oppositions (e.g. 2001, 2005, 2016, 2020) also allow excellent viewing opportunities.
What about 2009 through 2012?
Sorry, for 2009 the Earth is still catching up to Mars. The distance is closing but it's still over 280 million km away (see this neat real-time Earth Mars distance calculator).
Last December the two planets were on opposite sides of the Sun and almost 400 million km apart. The next oppositions in 2010, 2012, and 2014 are among the farthest and least interesting. So when the Mars Hoax email comes around in one of these poor years - enjoy a chuckle. Mars will continue to appear smaller and smaller until after 2012 when it begins to return to its regularly scheduled close oppositions. So in that sense, Mars is shrinking.
Click here for tables of Mars oppositions and closest approaches and a technical explanation at SEDS (Students for the Exploration and Discovery of Space).
Want to See for yourself?
Nothing helps like a visual. Try out the NASA/JPL orbit simulator, here. The reason I've used the asteroid Ceres to trick the simulator because you can't look up a planet or a moon in its database. Now you should:
A quick search of Google for Mars+Hoax gets 810,000 hits. There are pages on the Mars Hoax at both Wikipedia and Snopes.com. Here are what just a few knowledgeable people are saying about this hoax:
The diameters of Mars and our Moon are about 6752 km to 3470 km or just about 2 to 1. For Mars to appear the same size as our Moon it would need to be much closer to us. About twice as far as our Moon in fact. At that distance Mars would be inside the Earth’s Hill Sphere and we would either have a second moon or be in really big trouble (see the picture above).
On a Lighter Note
Planetary oppositions of Mars were featured in two Warner Brothers cartoons:
I received my first Mars Hoax email of the season last week and thought I should clear the air.
In fact not only is Mars not going to be this big, in one sense it is shrinking ...

Origins of the Mars Hoax
On August 27, 2003 Mars and Earth lined up in what is known as an inferior conjunction or opposition. This is a normal astronomical event which happens every 26 months. That year the opposition was special because it was closer than normal. A lot was made of the fact that at 55.7 million km it was the closest Mars and Earth had come in almost 60,000 years.
A more realistic view is that Mars and Earth oppositions bring the two planets within the wide range of 55 to 101 million km. But they only get to close end of this range every 7 or 8 oppositions (e.g. 1956, 1971, 1988, 2003, 2018, 2035, 2050). When Mars is in close opposition it is nearly twice as close and will appear nearly twice as big. During these close oppositions Mars will appear much brighter than normal but you will still need a telescope to see it. These close oppositions are the very best times to see Mars through a telescope. The neighbouring oppositions (e.g. 2001, 2005, 2016, 2020) also allow excellent viewing opportunities.
What about 2009 through 2012?
Sorry, for 2009 the Earth is still catching up to Mars. The distance is closing but it's still over 280 million km away (see this neat real-time Earth Mars distance calculator).
Last December the two planets were on opposite sides of the Sun and almost 400 million km apart. The next oppositions in 2010, 2012, and 2014 are among the farthest and least interesting. So when the Mars Hoax email comes around in one of these poor years - enjoy a chuckle. Mars will continue to appear smaller and smaller until after 2012 when it begins to return to its regularly scheduled close oppositions. So in that sense, Mars is shrinking.
Click here for tables of Mars oppositions and closest approaches and a technical explanation at SEDS (Students for the Exploration and Discovery of Space).
Want to See for yourself?
Nothing helps like a visual. Try out the NASA/JPL orbit simulator, here. The reason I've used the asteroid Ceres to trick the simulator because you can't look up a planet or a moon in its database. Now you should:
- Click the Orbits drop down and select in order: No Orbits, Earth, and Mars
- Turn off the Distance label
- Zoom in a bit to get Ceres out of the picture
- Set the Way-back machine to Aug 27th 2003 (use Date or just run it backwards using "<<")
- Rotate the frame so Earth and Mars are front and center
- Set the Interval beside the date to 1 year
- Step forward and back
A quick search of Google for Mars+Hoax gets 810,000 hits. There are pages on the Mars Hoax at both Wikipedia and Snopes.com. Here are what just a few knowledgeable people are saying about this hoax:
- We Need The Mars Hoax... The Universe Just Ain't Exciting Enough | Space Disco - June 10, 2009
- Mars as Big as the Moon 09 #2 | Alice's Astroinfo - June 5, 2009
- Mars. Moon. No. | Bad Astronomy - June 4, 2009
- The Mars Hoax Rides Again | Astroblog - May 12, 2009 (with fixed/parody hoax Powerpoint)
- Really, Mars will NOT be the size of the Moon in the sky! | Astroprof - May 2, 2009
- Mars Hoax Lasts Five Years | Cosmic Log MSNBC - August 26, 2008
- Please (Again)– Mars Will NOT Look As Big As the Full Moon | Universe Today - August 23, 2008
- Today is the day Mars isn’t as big as the Moon! | Bad Astronomy - August 26th, 2007
- Will Mars Look as Big as the Moon on August 27? Nope | Universe Today - July 25th, 2007
- The Zombie Mars Hoax That will Not Die | Astroblog - July 24, 2007
- Return of the Great Mars Hoax | Cosmic Log MSNBC - August 21, 2006
- No, Mars Won't Look as Big as the Moon in August | Universe Today - July 27th, 2006
- Mars Hoax | Astroblog - August 2, 2005
- No, Mars Won't Look as Big as the Moon | Universe Today - July 8th, 2005
- Beware the Mars Hoax | Science @ NASA - July 7, 2005
- Mars Attacks | Bad Astronomy - August 13, 2003
The diameters of Mars and our Moon are about 6752 km to 3470 km or just about 2 to 1. For Mars to appear the same size as our Moon it would need to be much closer to us. About twice as far as our Moon in fact. At that distance Mars would be inside the Earth’s Hill Sphere and we would either have a second moon or be in really big trouble (see the picture above).
On a Lighter Note
Planetary oppositions of Mars were featured in two Warner Brothers cartoons:
- "Rocket-Bye Baby" used a close approach to Mars in 1954 to set up a cosmic mix up where a Martian and human baby were switched.
- In the 1958, "Hare-Way to the Stars", Bugs Bunny foils Marvin the Martian's plan to blow up Earth with the Illudium Q-36 Explosive Space Modulator because it obstructs his view of the planet Venus.
Three Ring Carnivals (of Space #106, 107 , 108)
The most recent three carnvials at:
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CarnivalOfSpace
Sunday, May 31, 2009
Carnival of Space #105 @ Space Disco(very)
Ian O'Neill takes the helm at the Discovery Space and hosts the 105th Carnival of Space. This week there's lots going on from why people should go to Mercury, more Tunguska weirdness put in its place, a space elevator concept that leaves me spinning, and much more.
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CarnivalOfSpace
Monday, May 25, 2009
Carnival of Space #104 - The Arrow Edition
Welcome to ...
Carnival of Space#105 #104
... at Mang's Bat Page!
I'd like to thank Fraser for this my second time hosting the Carnival. While my first effort was a real blast, I do hope you all get a lift from this one.Carnival of Space
... at Mang's Bat Page!
This
Before we begin, I'd like to reflect on this amazing aircraft and its bittersweet legacy.
Arrow Reflections
In the 1950's Canada wanted a twin engine, all-weather, two seat, supersonic interceptor to defend against the Soviet bombers. The Arrow was our answer. Only it was never to be.
The Arrow was a source of national pride and shame for Canadians. An advanced fighter interceptor, widely believed to be superior to British and US projects. It incorporated many innovations including fly-by-wire, computer control, an integral missile system, and internal weapons pod. The Arrow was capable of exceeding Mach 2 with a 60,000 foot ceiling. It was even able to reach supersonic speeds without afterburners! A Mach 3, 80,000+ foot version was under study. The Iroquois engine being designed for the mark 2 Arrow was the most powerful turbojet in the world at the time. Ultimately the Arrow failed because of politics, changing roles, and a lack of buyers outside the country. For the US, Britain, and France - it was not invented there. Sadly, the five Arrows were reduced to scrap. There is even a conspiracy theory about a missing Arrow. The real tragedy was the damage to our aerospace industry and in true Canadian fashion the cancellation may have cost more than completing the program.
I grew up within sight of the production and test facilities. One of my mothers friends was a friend of Jan Zurakowski, the first test pilot, and I believe also one of the chase pilots. And when I was a child, I built models of the plane. Little did I realise that families living just down the street had been hurt by the 30,000+ layoffs and job losses resulting from the cancellation.
Others gained from Canada's loss. A group of 32 engineers went to NASA and worked on manned space programs. Others worked on the Concorde. The legacy of this project is an amazing tale.
And now the
Startup, Blueprints, Models and Test Flights
- Alan over at MSN's Cosmiclog shows how Young star trekkers shine. But it's not quite what you might expect.
- Ethan at Starts with a Bang! contributes "The Lazy Astronomer" on how you can start exploring the night sky with no knowledge and good pair of binoculars for less than $100.
- Rob at the Orbiting Frog wants to know how people got into astronomy by sharing how he got into astronomy.
- David at Robot Explorers recalls Project Hyreus a clever and impressive student designed Mars Sample Return mission.
- Lousie at "A Babe in the Universe" get a looks at NASA's full-scale “Moonbase” mock up under construction with the cylindrical and toroidal modules and docked lunar rover.
- The Bad Astronomer presents this unusual and awesome view of Saturn! There's a lot going on in the shadows and it takes someone with Phil's knowledge to explain it.
- The Lab Lemming catches on of those rare moments when both Scorpio and Orion are visible at the same time. Keep running oh boastful hunter ....
- Astroblogger presents this photo of the anomalously bright Comet C/2008 Q3 Garrad near a Globular Cluster.
- Nancy at Universe Today reports on The Brotherhood of Hubble Warriors: Jeff Hoffman Reflects on HST Repair Missions .
- Nicole at One Astronomer's Noise reflects on the STS-125 Hubble Repair and the different challenges facing terrestrial and space telescope repair.
- Bente at Planetbye has a little fun with a female perspective on the awesome Hubble fix.
- Steinn at the Dynamics of Cats shows a video of the STS-125 Hubble Wrap-up STS-125 Hubble Wrap-up.
- The Cosmiclog looks at why space repairs aren't easy.
- Mang (oh that's me) presents a third article using the JPL orbit simulator, this time looking at Strange Orbits: Quasi-satellites, Horseshoes, Corkscrews and Earth Stalkers - Earths Other Moons II. As an added bonus, meet Asteroid David Dunlap inspired by the fight to save Canada's largest telescope and observatory.
- Jazz Singer, Diane Nalini launched a new album "Kiss Me Like That" in Toronto on Sunday May 24th. The album features 13 songs bringing astronomical themes to Jazz. (h/t to Ray Khan)
- The Space Writer reviews the new Star Trek movie.
- Cosmiclog looks at the lighter side of spacewalking. And no, it is not boomdiada!
- Ian O'Neill has taken over the role of Producer at Discovery Space and the Space Disco blog replacing Dave Mosher. Good luck Ian (and Dave).
- We continue to learn from mistakes and disasters, this time Space Disco shows How the Chernobyl disaster may help plants grow on Mars.
- OrbitalHub presents Glory In The Sky a look at a science mission that will look at Earth?s energy budget and hopefully allow us to anticipate changes to the climate
- Cheap Astronomy presents a podcast "One Crowded Second" the first of a two part series on the time line of the Big Bang and subsequent evolution of the cosmos.
- Do you find you have less energy and are less active as you get older? Do you wonder why you never see grannies brake dancing? It turns out stars aren't that much different, find out about the interesting science of gyro-chronology.
- Bruce at 21st Century Waves looks at a mega-engineering project from the late19th and early 20th century and what we may learn about the future of manned spaceflight in "10 Lessons the Panama Canal Teaches Us About the Human Future in Space".
- Centauri Dreams looks at "The Hunt for Centauri Planets" about an ambitious but tracking low-key hunt for planets around the nearest star(s). In less than five years we might discover an Earth sized planet orbiting one of our nearest neighbours.
- Cosmiclog looks at the past and future of private space flight from Mircorp to Space-X in "The Past and future of 'New Space'".
- Out of the Cradle offers up an EVA interview with Paul Eckert about the 6th Space Investment Summit
- Cosmiclog presents a Time Travelogue looking at that staple of fantasy and science fiction from Dickens to Star Trek and the Terminator. It turns out that some of these scenarios may be testable at a quantum level.
- CumbrianSky looks at some historical events and asks what might have been if things had gone slightly differently?
- Music of the Sphere's provides insight into the "Super-cool Spacecraft" Herschel and Planck.
We now conclude our regularly scheduled Carnival and leave you with some more Arrow references:
- The Canadian Air and Space Museum in Downsview (Toronto)
- The Canadian Aviation Museum in Ottawa
- Wikipedia on the Arrow
- Wikipedia on Avrow
- An arrow site at avro-arrow.org
- A Video on the Arrow at google
- The Arrow site and links at the University of Saskatchewan Archives
- The Iron Warrior (U of Waterloo) looks back on the Arrow
- The Arrow at Fighter-planes.com
- The Arrow at Global Aircraft.com (suggested by a reader)
If you are in Toronto check out the Canadian Air and Space Museum where you can see a full sized replica of the Arrow. Or in Ottawa, the Canada Aviation Museum has some of the remaining components of the Arrow.You may want to read one of Peter Zuuring's books "The Arrow Scrapbook", "Arrow Rollout", or "Arrow Countdown".
There was also a 1997 made for TV movie called The Arrow starring Dan Ackroyd that was loosely based on the Arrow story.
So long until the next carnival!
| Space Carnival Chain | Last Week (103) : @ The Chandra Blog | Next Week (105) : @ Space Disco | Home Base : Carnival of Space | Universe Today |
<==== Don't forget to checkout the Unoffical Carnival of Space Search on the blog sidebar (near the top).
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CarnivalOfSpace
Tuesday, May 19, 2009
David Dunlap Asteroid
The main belt asteroid 70207 discovered in 1999 is now called 70207 Davidunlap. It orbits once every 3.7 yeas near the inner edge of the main astreoid belt and is 5 kilometers in size. You can see the orbit diagarm here.
The astroid was one of 62 discovered by Mike Collins, an amateur astronomer who lives in California. Mike is a supporter of the efforts to save the Dunlap Observatory and Park in Richmond Hill. He named the asteroid to recognize the "extraordinary effort demonstrated by the dedicated community of Richmond Hill for the past 20 months to save its greatest landmark".
h/t to Ray Khan
The astroid was one of 62 discovered by Mike Collins, an amateur astronomer who lives in California. Mike is a supporter of the efforts to save the Dunlap Observatory and Park in Richmond Hill. He named the asteroid to recognize the "extraordinary effort demonstrated by the dedicated community of Richmond Hill for the past 20 months to save its greatest landmark".
h/t to Ray Khan
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Astronomy
Strange Orbits: Quasi-satellites, Horseshoes, Corkscrews and Earth Stalkers - Earths Other Moons II
This time let's look at a number of very strange objects known as quasi-satellites and co-orbital bodies using the JPL orbit simulator.
Basically co-orbital bodies are objects that share an orbit but are too far apart for one to be a natural satellite or true moon. Even very large planets can't completely clear all of the debris out of their orbits. In fact, they create special opportunities for co-orbital bodies at what are known as the five Lagrange Points and through resonant orbits.
True Moons
Before we talk of false moons, we need to be sure of true moons. Natural satellites or true moons orbit inside a volume of space known as a Hill Sphere. This is where the gravity of a planet or other object dominates the gravity of a second more massive object like the Sun. It might help a bit to think of water running down a drain in a basin with two drains - the whirlpool is a little bit like a Hill sphere. (I'm sure there are problems with this analogy but it might make an interesting school science experiment.)
There are two points on the surface of a Hill Sphere where the gravity of the two main objects is in balance. These points are known as L1 and L2 and for the Earth-Sun system the sphere is about 1.5 million km (or 0.01 AU) in radius. While there are a number of types of orbits that will keep an object at L1 and L2, these aren't stable places and asteroids wouldn't remain there for long. However, it does turn out that L1 and L2 are very useful places to put satellites.
In practice a moon will be found well within the Hill Sphere of a planet.
Trojans (and Greeks)
The first and simplest type of false moon are called Trojans. These objects orbit at or near the L4 and L5 Lagrange Points which are placed equally forward and behind a planet on it's orbit forming an equilateral triangle with the two major objects (such as Earth-Sun or Jupiter-Sun).
The first Trojan asteroid was discovered in 1906 and named Achilles ( orbit diagram, Wikipedia ). Achilles, which leads Jupiter, and its fellows at L4 became known as the Greeks camp or the Greeks. And the Jupiter trailing asteroids at L5 became known as the Trojan Camp. There are even a couple of "spies" that were named before the convention was agreed upon.
Whenever you have one body in orbit around another you will have these points. It can be relative to a star and planet like the Sun and Jupiter, or even a planet and its moons. Saturn's moons Tethys and Dione each have Trojan moons. In theory, there could even be Trojan planets that could arise in situations like binary star systems.
Other than Jupiter, both Mars and Neptune have know Trojans. Earth has no know Trojans. Wikipedia has a list of objects at Lagrange Points.
And if you're wondering why I haven't mentioned the L3 Lagrange Point. That point lies on the opposite side of the larger object. Anything near there would be unstable. Beyond some science fiction like Journey to the Far Side of the Sun, there's nothing there.
Weird orbits - Truth is stranger than fiction
Finally, there are a variety of objects with very strange orbits. Some of these are called Quasi-Satellites with orbits that have been described as Horseshoe or Tadpole and Corkscrew shaped. Stranger still, some of these switch back and forth. Below are some of these:
Suspected space junk with weird orbits
These aren't in the orbits database but may be of interest:
Related Articles - Elsewhere
Basically co-orbital bodies are objects that share an orbit but are too far apart for one to be a natural satellite or true moon. Even very large planets can't completely clear all of the debris out of their orbits. In fact, they create special opportunities for co-orbital bodies at what are known as the five Lagrange Points and through resonant orbits.
True Moons
Before we talk of false moons, we need to be sure of true moons. Natural satellites or true moons orbit inside a volume of space known as a Hill Sphere. This is where the gravity of a planet or other object dominates the gravity of a second more massive object like the Sun. It might help a bit to think of water running down a drain in a basin with two drains - the whirlpool is a little bit like a Hill sphere. (I'm sure there are problems with this analogy but it might make an interesting school science experiment.)
There are two points on the surface of a Hill Sphere where the gravity of the two main objects is in balance. These points are known as L1 and L2 and for the Earth-Sun system the sphere is about 1.5 million km (or 0.01 AU) in radius. While there are a number of types of orbits that will keep an object at L1 and L2, these aren't stable places and asteroids wouldn't remain there for long. However, it does turn out that L1 and L2 are very useful places to put satellites.
In practice a moon will be found well within the Hill Sphere of a planet.
Trojans (and Greeks)
The first and simplest type of false moon are called Trojans. These objects orbit at or near the L4 and L5 Lagrange Points which are placed equally forward and behind a planet on it's orbit forming an equilateral triangle with the two major objects (such as Earth-Sun or Jupiter-Sun).
The first Trojan asteroid was discovered in 1906 and named Achilles ( orbit diagram, Wikipedia ). Achilles, which leads Jupiter, and its fellows at L4 became known as the Greeks camp or the Greeks. And the Jupiter trailing asteroids at L5 became known as the Trojan Camp. There are even a couple of "spies" that were named before the convention was agreed upon.
Whenever you have one body in orbit around another you will have these points. It can be relative to a star and planet like the Sun and Jupiter, or even a planet and its moons. Saturn's moons Tethys and Dione each have Trojan moons. In theory, there could even be Trojan planets that could arise in situations like binary star systems.
Other than Jupiter, both Mars and Neptune have know Trojans. Earth has no know Trojans. Wikipedia has a list of objects at Lagrange Points.
And if you're wondering why I haven't mentioned the L3 Lagrange Point. That point lies on the opposite side of the larger object. Anything near there would be unstable. Beyond some science fiction like Journey to the Far Side of the Sun, there's nothing there.
Weird orbits - Truth is stranger than fiction
Finally, there are a variety of objects with very strange orbits. Some of these are called Quasi-Satellites with orbits that have been described as Horseshoe or Tadpole and Corkscrew shaped. Stranger still, some of these switch back and forth. Below are some of these:
- 3753 Cruithne ( orbit Diagram, Wikipedia), sometimes described as Earth's second moon, follows one of these orbits. There is an interesting simulation over at the orbit and gravity simulator here that shows the long term effect much better.
- 2009 BD ( orbit Diagram, Strange Asteroid 2009 BD Stalks the Earth | Universe Today) a recently discovered Earth Stalker. Try centering on the Earth and zooming in all the way, hit play and watch the race. Remember, Earth's Hill Sphere has a radius of about 0.01 AU - you can see that BD doesn't get that close.
- 2003 YN107 ( orbit Diagram, Wikipedia) a small corkscrew meteoroid that switches between corkscrew and horseshoe orbits.
- (164207) 2004 GU9 ( orbit Diagram, Wikipedia) a large 200+m corkscrew asteroid with a very stable long term orbit.
- 2002 VE68 ( orbit Diagram, Wikipedia) A long term companion for Venus.
Suspected space junk with weird orbits
These aren't in the orbits database but may be of interest:
Related Articles - Elsewhere
- Quasi-Satellite information page - Uneversity of Western Ontario, Paul Wiegert - good info, animations, and movies of various co-orbitals
- Cork-screw asteroids - NASA
- The moon that went up a hill and came down a planet | Bad Astronomy - why the moon isn't a planet but could be if ...
- Pluto's big hill to climb | Bad Astronomy - a discussion of why orbital dynamic characteristics like clearing the neighbourhood and Hill spheres probably shouldn't be used to classify planets
Labels:
Astronomy
Sunday, May 10, 2009
Carnival of Space #102 @ The Spacewriter's Ramblings
The 102nd edition of the carnival is now up here. Enjoy the cotton candy and the rides!
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CarnivalOfSpace
Friday, May 8, 2009
David Dunlap Observatory slated to reopen in the IYA2009!
The observatory that confirmed the first black hole will reopen this summer for public outreach programs!
Congratulations to the folks at the Royal Astronomical Society of Canada!
For more read the RASC news item.
No word on any potential research.
Related Articles
Congratulations to the folks at the Royal Astronomical Society of Canada!
For more read the RASC news item.
No word on any potential research.
Related Articles
Saturday, May 2, 2009
Space badge resource for Girls and Boys
Ken Murphy over at Out of the Cradle wrote a piece on Girl Scout space badges in Scouting the Moon. The article also has some references to US Boy Scout Space Exploration merit badge and the interesting online resource meritbadge.org.
(See what you can find when you read Carnival of Space, h/t to Issue #101)
(See what you can find when you read Carnival of Space, h/t to Issue #101)
Labels:
Badgework,
CarnivalOfSpace,
ScoutBlogs,
SpaceExploration
Carnival of Space #101 @ Robot Explorers!
Hey folks! The Carnival has set up again, this time you can find it at David Portree's Robot Explorers!
David's blog has lots of interesting material on space exploration both proposed and actualized.
BTW. The host really liked my article on asteroid and comet near misses and impacts. Thanks David.
David's blog has lots of interesting material on space exploration both proposed and actualized.
BTW. The host really liked my article on asteroid and comet near misses and impacts. Thanks David.
Labels:
CarnivalOfSpace
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