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Comets Easy to find, but only if you know what to look for - Dark location Patience Methodical Careful. If you think you’ve found a comet, you should first Check a good atlas (galaxy, nebula, etc.) Check list of currently visible or other newly discovered comets (Websites)

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  • Comets

  • Easy to find, but only if you know what to look for -

    • Dark location

    • Patience

    • Methodical

    • Careful

If you think you’ve found a comet, you should first

Check a good atlas (galaxy, nebula, etc.)

Check list of currently visible or other newly discovered comets (Websites)

Check it out again the next evening - note any motion (position change)


  • If it passes all these tests, then send it in to the IAU Central Bureau for confirmation.

  • your name

  • your address and contact details (e-mail address)

  • date and UT time of observation

  • observation method (e.g., naked eye, visual telescopic observation, photographic, or telescopic CCD)

  • specific details on instrumentation (aperture size, f/-ratio, etc.) and exposures (type of film or CCD, length of exposure, etc.)

  • observation site (name of location, giving either city/town and state/province/country, or some other geographical name nearby); longitude and latitude and elevation above sea level can be useful

  • If all goes well and they confirm it, you’ll become Immortal!


Comet names Central Bureau for confirmation.

Still use the old discoverer naming system - but when too many are discovered by the same person (or project), this is too confusing

First part of the name

P/ - comet with period < 200 years

C/ - comet with period > 200 years

D/ - comet that disappeared

A/ - oops, an asteroid


Year of discovery, followed by 1/2 month of discovery code and order of discovery

January = A, B July=N,O

February = C, D August=P,Q

March = E, F September=R,S

April = G, H October=T,U

May = J,K November=V,W

June=L,M December=X,Y

On occasion some look asteroidal, and get a bit of an asteroid name added in.

C/2001 HT50 (LINEAR-NEAT) C/2001 Q4 (NEAT)

C/2002 O7 (LINEAR) C/2002 T7 (LINEAR)

2P/Encke 29P/Schwassmann-Wachmann 1

43P/Wolf-Harrington 65P/Gunn

157P/Tritton


Brightness of a comet and order of discovery

How do you measure it?

One method - defocus the telescope/binoculars

How bright should it be?

Depends on -

Distance from Sun

Distance from Earth

Towards/away from the Sun

Size/age of the comet

How close to the Sun in the sky


  • Comet brightness estimate and order of discovery

  • V = H + 2.5 n log (r) + 5 log D

    • V=integrated magnitude

    • H = magnitude if 1 A.U. from the Sun, 1 A.U from Earth, also considered the “absolute magnitude”

    • n = typically 4

    • r = Sun-comet distance (A.U.)

    • D = Earth-comet distance (A.U)


Orbital elements for comets – for orbit prediction/tracking

e = eccentricity (0-1) i = inclination (degrees)

T = date of Perihelion q = perihelion distance (AU)

W = longitude of the ascending node (degrees)

w = argument of the perihelion (degrees)


Why study comets
Why study comets? prediction/tracking

  • Primordial

  • Two populations

  • Influence of solar winds

  • Source of meteor showers

  • See break-ups

  • Unpredictable – potential impacts

  • They’re just cool


Comet mcnaught c 2006 p1
Comet McNaught C/2006 P1 prediction/tracking


17 p comet holmes
17/P Comet Holmes prediction/tracking


Asteroids prediction/tracking

+160,000 observed

+14,500 named


And how are asteroids named? prediction/tracking

Old names - Names of gods, goddesses, people (real)

New names - Year, 1/2 Month designation (same as comets) and order of discovery (also a letter, no I)

2008NA, 2008NB, 2008NC,....2008NZ,

2008NA1, 2008NB1,....2008NZ1

2008NA2, 2008NB2,................


Why study asteroids? prediction/tracking

Can determine radius/size using occultation events - very precise timing, location dependent.

Brightness variations - composition, rotation, size

Asteroids found by using before-after comparisons of a region.

Asteroids tend to be found in the ecliptic.


But some vehicles are prediction/trackingtougher


Meteorites - fragments of comets or asteroids prediction/tracking

Most common Stony

Macrometeorites - big ones, look for burned features, crusts, unusual location, color, metal detectors can help

Micrometeorites - small ones, rain down continually


Iron - Nickel Meteorites prediction/tracking


Martian Meteorites prediction/tracking


Micrometeorites prediction/tracking


  • Collecting micrometeorites prediction/tracking

  • Magnets

  • Collecting Dish/Surface

  • Dishes/Containers

  • Snow

  • Use microscope to distinguish micrometeorites from crap


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