Sunday, September 21, 2014

saturn overview

6th planet from the sun, second largest after jupiter
a gas giant

it has a slight yellowish color due to ammonia in the upper atmosphere
with faint bands (much less dramatic than jupiter's)


first view of saturn through a telescope:
unknowingly, i pointed the scope at a bright "star" rising in the east
and was shocked to see it had rings...
a shudder and a concrete sense that there really is more out there than we know.
there's something about the rings and the shadow they cast over the sphere that makes it appear much more like a perfect 3-dimensional structure than a simple disk. 

the gap in the rings is called the Cassini division.
the darker band outside the cassini division is called the Encke minimum.
there's a near mythical gap outside of that called the Encke division.
that is only visible from earth with under excellent seeing conditions with high quality optics.

the angle of the rings varies from year to year as saturn makes its 29.5 year orbit around the sun.
in 2002 they were maximally tilted with the south pole facing us
(about the time i bought my largest scope)

here's one of my earliest shots from 2004:

in 2009, they were edge-on
though many find this the worst time to view saturn
i found the iconic line made an interesting image:

the rings are now opening again
peaking in June 2017 with the best view of the rings and the north pole of the planet (this event will sell lots of telescopes ;)

there's something special about the north pole:
the dark patch at the north pole is actually hexagonal!
it is a persistent cloud pattern, similar to jupiter's great red spot
santa's helpers must be more mischievous on saturn
i've yet to see or image it, but as the north pole continues to tilt
towards us i'm hoping to catch it

saturn has 150 moons and counting
the largest, titan, is larger than mercury and contains it's own atmosphere as well as hydrocarbon lakes.
titan casting shadow on saturn's surface:

9 or 10 can be seen thru an amateur telescope

enceladus is notable for salt water geysers which contribute to saturn's rings

more on saturn:

Saturday, September 6, 2014

M 24, it's full of stars

"my God it's full of stars"
-Dave Bowman's final words prior to entering the monolith in 2001: a space odyssey.  contrary to my recollection, the line occurred only in the book version, not the movie, but was grafted into the movie as a flashback in the opening of 2010.  

Messier object 24, a/k/a the sagittarius star cloud,  isn't really a star cluster, it's just a bright patch of stars in the milky way surrounded by dust.  it can be thought of as a hole in the dust, allowing us to see much deeper towards the center of our galaxy.  (no frank, you can't see the black hole).  The bright patch can be seen with the naked eye in skies dark enough to see the milky way as a bright patch above sagittarius

the patch of red, suggested there was some glowing hydrogen in the surrounding gas, so i decided to shoot it with an Ha filter:

Here's a combined view:

interestingly i see an Ha wall along the upper right margin of the star cloud
that is more evident in the HaRGB than the Ha itself.

if it weren't full of stars it would look like this:

Lastly here's a close up of the open cluster in the upper left portion of the star cloud i shot a few years ago:

-bill w

image details:

FS 60c @ 254 mm 5.23"/px full size
field approximately 2.5x3.5 degrees
Hutech IDAS, Chroma Loglow, Astrodon 5nm Ha filters
SX H9C, ASA DDM 60 unguided
4 panel mosiac composed of approximately 17 5 minute subs RGB
15 5 minutes subs Ha
newport beach, ca

more than you wanted to know about 2001:

Thursday, September 4, 2014

Delta Aquilae is 50 light years away

Aquila, the eagle, is a summer constellation. 
It can be found here in the summer evenings section:

It’s brightest star, alpha aquilae, a/k/a altair, forms one of the corners of the summer triangle.  A huge right triangle seen overhead during summer nights. 
Delta aquilae is at the center of the eagle.  At visual magnitude 3.36 it can be seen with the naked eye in good viewing conditions.

It is 50 light years away. 

Einstein’s theory of special relativity.  Basically states that the speed of light is the same for all observers.  Consider a space ship moving away from us at half the speed of light.  We shine a bright pulse of light into space.  After a year the light has traveled one light year away from us, while the space ship has traveled half a light year.  The pulse of light is half a light year from the ship.  So if the light has only traveled half a light year from the ship, how can its speed relative to the ship be the same?  Speed=distance/time.  So the solution is that the ship has only experienced half the time we have on earth—time has slowed down. 

Consider a photon leaving delta aquilae 50 years ago.  Some of us have experienced 50 years waiting for its arrival today.  But the photon, traveling AT the speed of light experienced no time at all. 

Something to think about for this day.  

Imaging details.
FS 60c @ 254 mm 5.23"/px full size
Chroma Loglow filter
SX H9C, ASA DDM 60 unguided
13 5 minutes, 24x30s, 24x3s
"diffraction spikes" added in processing for emphasis
newport beach, ca