Pluto
was discovered photographically on 1930 Feb 18th by Clyde Tombaugh at Lowell
Observatory -Arizona after a long search and is the remotest planet in
the Solar System.
Its eccentric orbit is inclined 17o
to the plane of the ecliptic [occupied by the remaining planets] and varies
from 29.7A [perihelion] to 49.2A [aphelion] from the sun [Earth is 1A or
8-light minutes from the sun] in a orbital period of 247.7yrs.
The planet past perihelion in 1989 and now
begins its slow journey even further from the sun. Pluto is currently
a faint mag 14 'star' in Ophiuchus visible low down from UK skies during
the summer months. It can be glimpsed through a 8-inch aperture telescope
in transparent skies aided by this finder chart.
The planet can be recorded with a much smaller
aperture camera lens shown piggybacked on my 30cm Meade SCT.
2004 June 27: Pluto recorded after
a two year break with its feeble spectrum in white box - the camera setup
to record spectra of nearby Nova Oph 04 and Var Her 04 - a possible
new cataclysmic variable [CV] star with nova-like outbursts.
2002 July 13/14/21: Pluto through
haze via 30cm Meade LX200 in 60s and 4m exposures.
2002 July 11/12: Pluto moves over 77 minutes
against the star background in average seeing and transparency at f/6.3
focus of Meade LX200.
2002 Jun 22/26: Pluto moves ! over
4 days. The remotest planet positively recorded in 3m exposures with a
regular camera lens of 48mm aperture [f/2.8 135mm fl + x2 tele-extender
= f/5.6 270mm fl] coupled to Starlight Xpress HX5 CCD and piggybacked on
LX200. It's highlighted here in Bas Relief to show the feeble mag
14 planet in 6m and 12m co-added exposures. Strong interference from nearby
full moon and drifting cirrus cloud on first evening so results impressive
as it needs a 20cm aperture or larger telescope just to glimpse the planet
visually.
2002 Jun 18: Pluto recorded after an absence
of three years but it's still in Ophiuchus now between eta and zeta Oph.
The close double-star components [centre-left] are both mag 15.9 [Megastar].
1999 July 5: Pluto low in Ophiuchus/Scorpius
borders showing its retrograde motion over 47 hours - actually the greater
motion is that of Earth on the fast 'inner' track !
text & images copyright - Maurice Gavin 1999-2004