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From: TerryMoselaol.com
Date: Sat, 25 Jun 2005 20:03:21 EDT
Subject: Amazing conjunction, ISS

Hi all,

Have you seen the lovely conjunction of Venus, Mercury & Saturn yet? They're 
getting really close! I just glimpsed them earlier this evening (25th) through 
wispy cloud, but Saturn was very faint compared even with Mercury.
   But the best is yet to come!
   On June 26, at 22.30 BST, when the sky is reasonably dark, Mercury & Venus 
will be only 14' 15" apart - less than half the diameter of the Moon! Saturn 
will be getting harder to see, as it's now even closer to the Sun than the 
Venus-Mercury pair, 1 deg 32' away to the lower right (P.A. = 225 deg)
   The very closest approach of Venus & Mercury takes place at 16.45 BST on 
27 June; that's still daylight here of course. But if you have an equatorially 
mounted telescope, & setting circles, you should be able to locate Venus in a 
wide field eyepiece, or in a good optical finder. If you can do that, look for 
Mercury only 3' 55" away, at P.A. 220 deg, in a medium power eyepiece. That's 
only about 1/8 the diameter of the Moon at perigee! It's less than 5 times 
the diameter of Jupiter! The attached JPEG image shows their correct relative 
sizes and separation, although it's rotated anticlockwise to fit better on your 
screen. A good telescope, particularly a well-baffled refractor, should show 
Mercury as well as Venus, if the sky is very transparent.
   Even without an equatorial mount, if you can find Venus a good quality 
well-baffled telescope might still show Mercury, in a good sky. This is where a 
proper optical finder (e.g. 7x50 or 10x50), properly aligned, shows its worth!
   Be VERY VERY careful not to get the Sun in the field of view of either the 
main telescope or the finder while you're looking for Venus! Even the 
briefest glimpse of the Sun through either will cause serious eye damage, probably 
blindness! So just don't risk it.
   If you can't see them then, your chances steadily improve as the Sun gets 
lower each hour, darkening the sky, although the distance between Mercury and 
Venus will also gradually increase. The following details give you an idea 
what to look for. P.A. = Position Angle of Mercury, from Venus, measured from 
North, through East.
17.00 BST: sep = 3' 56", P.A. = 220 deg.
18.00 BST: sep = 4' 00", P.A. = 207 deg.
19.00 BST: sep = 4' 10", P.A. = 198 deg.
20.00 BST: sep = 4' 27", P.A. = 189 deg.
21.00 BST: sep = 4' 49", P.A. = 182 deg.
21.30 BST: sep = 5' 02", P.A. = 179 deg.
22.00 BST: sep = 5' 16", P.A. = 176 deg.
22.30 BST: sep = 5' 30", P.A. = 174 deg.
   Even at 22.30, when the sky is fairly dark, and you can't really miss 
seeing them if the sky is clear, that's still a very very close conjunction! - 
it's between 1/5 and 1/6 the diameter of the Moon! Saturn will be 2 deg 19' away, 
at P.A. 248 deg.)
   Let's have your observations and digital photos - send them to me & I'll 
forward them to Andy McCrea for STARDUST, and to the IAA website, or send 
direct to , and .
   Good Luck!

The ISS continues its good series of late-night passes over Ireland: details 
for your own location (and for Iridium Flares, etc) are at <
   For example, there are two on Sunday night/ Monday morning, at about 01.30 
/ 01.35, and again at about 03.05 / 03.10. 
   In a few days some will also be visible before local midnight, as the 
morning passes merge gradually into a series of evening passes.

Clear Skies,

Terry Moseley


Last Revised: 2005 June 28th
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