Venus & Merc have same phase!

Just left the telescope after some lunchtime viewing of Venus and
Mercury through cloud breaks.

To my surprise both appear near identical phase eg 'half' or a little
less although Mercury tiny compared to Venus of course.

Megastar quote Venus22.8"diam; 53% phase ; Mercury 6.8"d; ph54%

Used Meade 12"LX200 x160 controlled by Megastar software eg click on
screen object to GOTO . [I leave 'dongle' in LX200 when not in use -
on removal scope already aligned and ready to GOTO].

On Fri, 26 Mar 2004 14:24:11 GMT, (Maurice Gavin)
wrote:

Just left the telescope after some lunchtime viewing of Venus and
Mercury through cloud breaks.

To my surprise both appear near identical phase eg 'half' or a little
less although Mercury tiny compared to Venus of course.

Megastar quote Venus22.8"diam; 53% phase ; Mercury 6.8"d; ph54%

Used Meade 12"LX200 x160 controlled by Megastar software eg click on
screen object to GOTO . [I leave 'dongle' in LX200 when not in use -
on removal scope already aligned and ready to GOTO].

Grabbed them last night Maurice

http://homepage.ntlworld.com/p.lawrence1/Venus/m-v250304.jpg

Never Toucam imaged Mercury before and only did so because of the
Moon. Last night the Moon was 9 degrees from Venus. Mercury was 27
degrees away on the other side - i.e. towards the horizon. If you
drew a line from the Moon through Venus, and bent it 20 degrees
towards the horizon, Mercury could be had 3x the Moon-Venus distance
away. Hands extended with fingers used as measuring gauges - there it
was. Of course I could just as easily have gone out and got a GOTO
;-)

--
Pete Lawrence
http://www.pbl33.co.uk
Home of the Lunar Parallax Demonstration Project

"Maurice Gavin" wrote in message
...
Just left the telescope after some lunchtime viewing of Venus and
Mercury through cloud breaks.

To my surprise both appear near identical phase eg 'half' or a little
less although Mercury tiny compared to Venus of course.

Megastar quote Venus22.8"diam; 53% phase ; Mercury 6.8"d; ph54%

If you picture the geometry, both will have the same phase when they are
highest in the sky (or when both are just barely above horizon at sunset).

Clear Skies

Chuck Taylor
Do you observe the moon?
Try the Lunar Observing Group
http://groups.yahoo.com/group/lunar-observing/
Lunar Picture of the Day http://www.lpod.org/
************************************


Used Meade 12"LX200 x160 controlled by Megastar software eg click on
screen object to GOTO . [I leave 'dongle' in LX200 when not in use -
on removal scope already aligned and ready to GOTO].

On Fri, 26 Mar 2004 14:55:54 +0000, Pete Lawrence
wrote:

On Fri, 26 Mar 2004 14:24:11 GMT, (Maurice Gavin)
wrote:

Just left the telescope after some lunchtime viewing of Venus and
Mercury through cloud breaks.

To my surprise both appear near identical phase eg 'half' or a little
less although Mercury tiny compared to Venus of course.

Grabbed them last night Maurice

http://homepage.ntlworld.com/p.lawrence1/Venus/m-v250304.jpg

Of course I could just as easily have gone out and got a GOTO;-)

Pete Lawrence

Nices images Pete - especially liked Mercury and see you're doing a
little spectroscopy by capturing atmospheric dispersiong. To negate
this effect had you tried dumping say blue and green files?
BTW - you wouldn't have found Mercury yesterday lunchtime by
starhoppingg.

On Fri, 26 Mar 2004 10:51:11 -0800, "CLT" not@thisaddress wrote:

"Maurice Gavin" wrote in message

To my surprise both appear near identical phase eg 'half' or a little
less although Mercury tiny compared to Venus of course.

If you picture the geometry, both will have the same phase when they are
highest in the sky (or when both are just barely above horizon at sunset).

Could you explain???

Chuck Taylor

On Sat, 27 Mar 2004 09:33:47 GMT, (Maurice Gavin)
wrote:

Nices images Pete - especially liked Mercury and see you're doing a
little spectroscopy by capturing atmospheric dispersiong. To negate
this effect had you tried dumping say blue and green files?

I find the best way to get rid of these effects is simply to do a
monochrome capture. However, I was quite taken by the variation in
colour between Mercury and Venus. Quite noticable.

BTW - you wouldn't have found Mercury yesterday lunchtime by
starhoppingg.

Wanna bet? ;-)
--
Pete Lawrence
http://www.pbl33.co.uk
Astronomy and digital imaging website (last update 21-03-04)

In article , Pete Lawrence
wrote:
On Sat, 27 Mar 2004 09:33:47 GMT, (Maurice Gavin)
wrote:

Nices images Pete - especially liked Mercury and see you're doing a
little spectroscopy by capturing atmospheric dispersiong. To negate
this effect had you tried dumping say blue and green files?

I find the best way to get rid of these effects is simply to do a
monochrome capture.

A better solution would be to move (and scale?) the R & B to make them
align with G. I don't know which, if any, software packages offer this.
--
Jim Easterbrook http://astro.jim-easterbrook.me.uk/
N51.36 E0.25

In article , Maurice Gavin wrote:
On Fri, 26 Mar 2004 10:51:11 -0800, "CLT" not@thisaddress wrote:

"Maurice Gavin" wrote in message

To my surprise both appear near identical phase eg 'half' or a little
less although Mercury tiny compared to Venus of course.

If you picture the geometry, both will have the same phase when they are
highest in the sky (or when both are just barely above horizon at sunset).

Could you explain???

I'm not Chuck, but this is how I think it works...

Imagine a triangle with vertices at Mercury, Earth and Sun. Venus
appears furthest from the sun, as seen from earth, when the angles E-M-S
and E-S-M are equal. In this case the angle E-M-S is nearly a right
angle, so Mercury is illuminated side on. A similar argument holds for
Venus.

If both are high in the sky, then both appear furthest from the sun, so
both are illuminated side on.
--
Jim Easterbrook http://astro.jim-easterbrook.me.uk/
N51.36 E0.25

On Sat, 27 Mar 2004 13:07:54 -0000, Jim Easterbrook
wrote:

In article , Pete Lawrence
wrote:
On Sat, 27 Mar 2004 09:33:47 GMT, (Maurice Gavin)
wrote:

Nices images Pete - especially liked Mercury and see you're doing a
little spectroscopy by capturing atmospheric dispersiong. To negate
this effect had you tried dumping say blue and green files?

I find the best way to get rid of these effects is simply to do a
monochrome capture.

A better solution would be to move (and scale?) the R & B to make them
align with G. I don't know which, if any, software packages offer this.

I do this on occasion with my Venus images. However, I think that
Mercury was a little beyond redemption.
--
Pete Lawrence
http://www.pbl33.co.uk
Astronomy and digital imaging website (last update 21-03-04)

Jim Easterbrook wrote:
A better solution would be to move (and scale?) the R & B to make them
align with G. I don't know which, if any, software packages offer this.

Registax.

Best,
Stephen

Remove footfrommouth to reply

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