Murphy's Laws of meteor astronomy

• Four mutually exclusive things: clear skies, no moon, no school(work) and major shower peaks.
• Meteor activity will be low until you decide to take a break.
• Meteor activity will be low until you fall asleep.
• While watching a major shower you will see only one meteor in several minutes, many will appear while you're recording the lone meteor you saw
• If you're facing north, most meteors will appear in the south.
• When you turn south, most meteors will appear in the north.
• When you install a fisheye meteors will disappear altogether
• When a fireball appears you will invariably be looking 180 degrees in the wrong direction.
• When a fireball appears you will invariably be looking at the ground.
• When a fireball appears you will invariably be recording a +5m meteor.
• When a possible minor shower meteor appears you will remember its path, but you will forget its direction.
• When a possible minor shower meteor appears a gust of wind will appear out of nowhere and blow your charts downhill.
• Meteor activity will be nonexistent until you must take a sanitary break.
• Meteor activity will be low until you become really hungry.
• The diameter of stars is linearly proportional to your teff.
• The number of meteors is exponentially proportional to your teff.
• During an uncharacteristic stretch of clear skies the peak night will be cloudy.
• Your taperecorder will die during the most active period.
• Your pencil will die during your most active period.
• Your torch will die during the most active period
• A possible minor shower meteor will invariably appear in Camelopardalis.
• A fireball will invariably appear in Camelopardalis.
• A fireball will invariably appear in your camera's field of view in between exposures.
• A fireball will invariably miss your camera's field of view by a couple degrees.
• When a fireball appears it will invariably appear in the part of the sky that's not on your charts.
• When it's clear your LM will be poor.
• If your LM is great you will either become sleepy or fog will lift.
• Fog will lift anyway.
• If the weather is poor and you go chasing clear skies, it will eventually be clear home.
• The largest telescopes you've ever seen will invariably be present during the peak night.
• The radiant of a very weak possible new shower will invariably be best placed for observations in early April evenings.
• Two mutually exclusive things - clear skies and no moon
• If it's clear all day, it'll be cloudy that night.
• You will invariably be grounded due to committments during those LM7 nights.
• If it's clear and there's no Moon, it will be brutally cold and the wind will be blowing like a hurricane
• When you catch a fireball on your camera the photo will be out of focus.
• Perfect photos will be ruined by the lab.
• The product of the number of shower meteors and the desire for their processing has a constant value.
• If you observe 364 nights a year, the outburst will happen in the 365th.
• If you observe 365 nights a year, there will be no outburst.
• Your wife/husband/boyfriend/girlfriend's birthday will be on January 3, August 12, November 18 or December 14.
• If you observe from your backyard your neighbour's dog will have a sleep disorder.
• If you observe from your backyard your neighbour will have a sleep disorder and spend the night in a brightly lit kitchen, which will invariably be facing your backyard.
• If it's been clear whole July and up to August 12, the latter date will invariably be cloudy.
• If it is by some coincidence clear it will be unseasonably cold.
• If winter has been mild so far there will be a blizzard on December 14 and your favorite observing spot will be burried under a meter of snow.
• You will catch a cold on December 13.
• You will get over the cold quickly but you will be ill again on January 3.
• Your mid-term exam will be on January 4.
• When you arrive to your favorite spot for the Geminids you will forget: gloves, extra socks, warm drinks.
• You won't observe the Geminids since it's full Moon.
• If it's not full Moon you will be under the only cloud within miles
• You will always enjoy clear skies when the Moon is full. You won't when it is new Moon.
• If an outburst is predicted it will occur 16 hours earlier and you will miss it.
• If you prepare and observe 16 hours earlier there will be no outburst.
• If its crystal clear there will be a lone patch of cirrus passing during the outburst.
• It will always be clear during the nights before the maximum from a big meteor shower. The maximum night will be clouded out.
• There is no such thing as luck.
• If there is, luck has nothing to do with it.
• Leonids don't peak over your longitude.

(adapted from thread in sci.astro.amateur)

• from Stephen Tonkin:

The Law of Inevitable Shrinkage:
Telescope- or truss-tubing, if cut to length, will be too short.

Tonkin's Law of Small-part Replication:
When you have re-assembled the piece of expensive kit you promised to clean and recollimate for a friend, there will always be one screw/nut/washer/bush left over.

Waldeman's Laws:

• 1st Law: The skies are never clear within 3 days of nemoon, since there is not enough solar energy reflected off the moon to dissipate the clouds.
• 2nd Law: Rare astronomical events usually occur within 3 days of full moon and/or within 30 apparent degrees from the sun (gravitational interpretation of Murphy's law).
• 3rd Law: When observing, the object you want to see will always be below the horizon or less than 10 degrees from the horizon with the most light pollution (since frustration is related to entropy, it must always increase).
  
• 4th Law: Supernovae, comets, and asteroids are always discovered by someone else (because no matter where you are, the sun will always set earlier somewhere else, and therefore someone else will find it first).
• 5th Law: 90 percent of meteors occur behind you when everyone else is facing you (so they can all say, "ooh!... You missed a good one!")

The Laws of Selective Gravitation:

• 1st Law: Heavy objects land where they can do the most damage - where an excellent, lovingly figured, diffraction-limited primary is either the recipient of the heavy object or, indeed, is the object itself.
• 2nd Law: Small objects land in the place from which they are most difficult to retrieve - well known to anyone who has inadvertently loosened something like an eyepiece-retaining screw too far, or attempted to change eyepiece filters with either gloved or cold fingers.

Law of Selective Observation:
The next supernova will occur in a galaxy that you observed on the previous clear night.

Law of Selective Declination:
The most interesting astronomical event of the year will occur at a declination that is below the horizon of your observing site.

Law of Selective Vegetation:
The neighbour's tree always migrates to precisely the right place to occult your target object.

Sod's Law (Astronomer's variant of):
A dropped optic will always land surface-side down, unless it is either capped or dropped for the express purpose of proving this law.

Crighton's Law of Loss:
Lost items stay lost until either a replacement is obtained and used once or the item is no longer required - Crighton's Law also explains why things like spare drive batteries and cable-releases are found just as dawn twilight extinguishes 2nd mag stars.

Gumperson's Constant (Flanagan's Finagling Factor):
The factor by which you multiply the answer you got in order to obtain the answer you should have got - is obviously employed by many mass- producers of astronomical optics and one can't help wondering if this was the true reason for the figure of the HST mirror.

Law of Temporary Loss:
A lost item (e.g. LPR filter) will stay lost until it is either replaced or no longer required.

Law of Averted Vision:
The brightest meteor of the night will occur behind you, visible only to the people to whom you are talking at the time. (This is true for all observers, including those to whom you were talking.)

Lunar Radiation Principle:
Deep Sky observers will find that the clearest nights are around Full Moon, when the lunar radiation is sufficient to drive off the clouds and haze.

Daylight Conundrum:
With the unique exception of total solar eclipses, the year's ten most interesting astronomical events will occur when the Sun is above your horizon, unless it is raining.

Kahn's Axiom:
When all else fails, read the instructions - increasingly important as astronomical kit becomes more technologically complicated.

• from Scott McCluney:

Gravity increases exponentially as you approach an exposed mirror. Things like eyeglasses, screwdrivers, and pliers will be drawn to it.

• from Jeff:

Your once-in-a-lifetime chance to see a total eclipse, and a dark thunderstorm covers you.

• from Dave Storey:

Co-efficient of friction between hand and EP is inversely proportional to cost of EP raised to some power (around 2.5?).

On any mostly clear observing horizon, the one obstructing tree/streetlight/house will always migrate to the position where it obscures what you really want to look at.

Probability of clear night is proportional to cube of phase (% illumination) of the moon .. except maybe for lunar observers, where more complex relationship applies. Batteries only expire when it is a) dark, and b) miles to nearest store. Nearest store will stock all batteries except the required size, or will have n-1 of required size, where n is number needed for functionality.

• from Preston Scott Justis:

Precision Polar Alignment of this telescope for Long Exposure Astrophotography may result in high winds and (or) clouds.

• from Michael A. Covington:

My presence has the following effects on the weather at observing sites:
My first visit to a remote part of the world is usually accompanied by bizarre weather. For instance, Seattle had a whole week of clear weather the first time I went there. And the first time I set foot in England was, up to the time, the hottest day England had *ever* recorded (or so I'm told). If I have a new telescope, it will be hazy for 6 weeks. If there is a total solar eclipse, solid overcast at the moment of totality is assured. (Don't worry, I'm staying in America for August 1999!)

• from Colin:

Went to "bump" a cat once away from my leg while observing, guess again.....SKUNK !

•  from Bill Cotten:

All guide stars (when manually guiding), are variable stars. This is not noticed until you are 15 minutes into a 90 minute exposure. Naturally the stars period is equal to your desired exposure time AND you always start guiding just as soon as it begins it's rapid drop off in brightness to 25th magnitude. As your guide star reaches 15th magnitude, you close the shutter after only 30 minutes. It goes without saying that your composition, focus, polar alignment and guiding accuracy were dead on perfect but you don't realise this until the film is back from the lab and your "Pleiades Nebulosity" shot barely shows enough nebulosity to convince *you* that it is there.

•  from Sean Barr:

I had just got my first good scope after five years of using a sears refractor (brrr!). I set up and got ready for a long night of teaching myself what I had been missing, or so I thought. For those of you who don't know I live in Newfoundland, Canada. A conpany called Sprung had built a huge (5 or 6 football field sized) greenhouse complex 1/2 mile from my house and planned to turn on the SODIUM lights that very moment. I suddenly had no trouble reading my maps, bathed in 1/4 daylight and watching a huge collumn of sickly yellowish light to the south. I had lost 3/4 of the night sky in a heartbeat. Almost two years later they went bankrupt and the lights went out. How would you have handled it? TWO YEARS LOST!