Venus

Venus captured by Mariner.
-Image credit NASA

When I first moved from the high deserts of Nevada to The tropical warmth of Florida I thought I would never have the ability to get an image of Venus. I was wrong.

Venus is the second planet to the the sun, orbiting at an average distance of 67 million miles (108 million kilometers), Venus is 0.7 astronomical units away from the sun. (1AU is the same as earth’s orbit.)^[1] In order to see it you have to look right before sunset and right before sunrise, depending on what time of year it is.  It is usually low in the horizon. Being in Nevada I had little time to catch it,  usually about an hour or 2 before it went too low on the horizon. When I moved to Florida I forgot to take into account how far south I was. I assumed the trees would obscure my view or shorten what was already a short viewing time. Fortunately being this far south moved it up considerably in the horizon!

Before I got into some things I learned on this while trying to observe and photograph, I want to go into the in depth for everyone on the planet itself.

Venus Facts:

First off how big is it? Venus has a radius of 3,760 miles (6,052 kilometers), which is about as big as earth’s but slightly smaller.^[1] It is similar in size however its mass is 81.5% of Earth’s.

The most notable and interesting thing about Venus is it’s atmosphere. The atmosphere is 96.5% carbon dioxide, with most of the remaining 3.5% being nitrogen.^[2] The thick atmosphere of Venus is one of the best examples of a greenhouse effect. It traps the sun’s heat, and causes Venus to have the highest temperature of all the planets in the solar system. The surface temperature gets higher than 880 degrees Fahrenheit (470 degrees Celsius). While it is the hottest planet the many layers of the atmosphere has layers with different temperatures. About 30 Miles from the surface of the planet the temperature is similar to earth’s.^[1] Oddly in stark contrast, at an altitude of about 125 kilometers above the surface, the Venus Express probe has recorded, the temperature drops to a chilly -175°C^[3] This atmosphere is so thick that the atmospheric pressure is ninety times that of Earth.

© 2005 Pearson Prentice Hall, Inc

This same atmosphere and heavy clouds are the cause of so much difficulty taking the photographs, which I will cover in a minute. The following two data sets show the difference between first Earth’s atmosphere and then Venus.

Synthetic Atmosphere Absorption Spectrum. By The author of the work and Hitran on the Web Information System, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=20649351

Synthetic Atmosphere Absorption Spectrum. By The author of the work and Hitran on the Web Information System, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=20649351

The Surface is pretty barren and rocky, Photographs are difficult to get of the planet’s surface due to the extreme heat. The probes last a short time before overheating and ceasing to function. Here are a few photos of the surface:

The surface of Venus as seen by the Venera 13 spacecraft.
Image credit Russian Aviation and Space Agency, now known as the Roscosmos State Corporation

The surface of Venus as seen by the Venera 13 spacecraft. The top picture shows the actual color of the surface. This orange tint is due to the cloud cover and how it filters the light to the surface, so this is how it would look if you were standing there.  The bottom photograph shows how the surface would look if it was under earth’s lighting conditions.

A larger view is here:

surface image – Image credit: Russian Aviation and Space Agency, now known as the Roscosmos State Corporation

What does it sound like? The Russians sent the Venra series of probes to the planet and from what I have been able to uncover is that there was a Venra 14 with microphone installed. this is the first probe to record sounds from another plant with in our hearing range. I am linking the audio link here .

The Upper atmospheric winds are pretty strong. The winds have been recorded at about 224 miles (360 kilometers) per hour. Atmospheric lightning bursts light up these quick-moving clouds. Speeds within the clouds decrease with cloud height, and at the surface are estimated to be just a few miles per hour.

The Planet has a weak magnetic field due to it’s slow rotation despite having an iron core. It has no moons and no rings around it. . .^[1]

The surface elevation of Venus is shown. The lowest regions are marked in purple, the mid-elevations in green, and the highest parts in yellow. The gray parts are where the mapping by the Magellan spacecraft was incomplete.  Image credit NASA.

Venus Orbits the same direction but the planet rotates opposite of earth. Venus and Uranus rotate the opposite direction of the rest of the planets.^[4]

Orbit of venus
Image credit: By Lookang many thanks to author of original simulation = Todd K. Timberlake author of Easy Java Simulation = Francisco Esquembre (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)%5D, via Wikimedia Commons

Phases of Venus

Due to it being closer in orbit to the sun than Earth, we see it in phases much like the moon. Honestly instead of explaining the retrograde and using a whole bunch of math and words one picture on this is easier.

The phases of Venus
-created by Rachel Knott using NASA material.

Photographing Venus

Currently my mount had to go back to Celestron for warranty repair. While trying to take photos of Venus I had the same issue arise as many other nights, hence my slow article output and not many photos this year. Taking photos with it has been a real challenge when it just stops tracking and is not responsive.

I had photographed venus a while back using the 6″ scope, my 6SE, and had the challenge of getting it before it fell to low on the horizon.

Venus taken in Northern Nevada with a Celestron 6se

What I didn’t take into consideration when using the 1100 HD Edge was how much of a light bucket it is. When looking at the moon, for example, it physically hurts to look with out using the moon filter. I attempted to use filters when recording the video to be thrown into Autostakkert2, but this scope pulled in so much light that it washes any detail out. I was left with some nice phases.

Taken 1-14-2017

Taken 1-14-2017

Taken 1-14-2017

Taken 1-14-2017

As you can see the lesson from this is that while the scope aperture being large is nice, it can washout color and leave you with not a whole lot of detail. I took these using the red, blue and light yellow filters to try to get different detail. Honestly, not using any filter was a complete wash out and it was so bad it  was hard to tell where the terminator was on the planet.

The next step I am going to try is to mount the 6se on the mount when it returns and see if I can get the color and cloud detail.  I am going to attempt this between classes and see if I can do anything with the good old 6SE Nextstar mount.  What this lesson should show is that there is not one telescope or one piece of equipment that does everything. As you expand your equipment, don’t get rid of anything unless you have no choice!

As far as equipment, I used the NCelestron C1100 HD Edge, the Celestron 95506 Skyris 236C CMOS camera and the yellow, red and blue filters. Unlike in the 6se, the type of filter did absolutely nothing except show the terminator, I will absolutely revisit this with the 6se.

Speaking of Planetary Filters, What filters should you use? I have a guide here (editorial note:  as of today I have to write this article, which will be next, I just am keeping it as a place holder. )

References;

1. Venus: In Depth,  NASA, http://solarsystem.nasa.gov/planets/venus/indepth on line, accessed Febuary 6, 2017.
   

2. “Atmosphere of Venus”. The Encyclopedia of Astrobiology, Astronomy, and Spaceflght. Retrieved 29 April 2007.
3. Mahieux, A. “Densities and temperatures in the Venus mesosphere and lower thermosphere retrieved from SOIR on board Venus Express: Carbon dioxide measurements at the Venus terminator.” Journal of Geophysical Research, vol. 117, E07001, 15pp (2012). doi:10.1029/2012JE004058

4.  Squyres, Steven W. (2016). “Venus”. Encyclopædia Britannica Online. Retrieved 7 January 2016.

Planet in Focus: Venus

Venus

Venus, Image credits NASA

Venus is the second closest planet to the sun and is almost as big as the earth. Oddly Venus rotates backwards in relationship to most of the planets giving it a sunrise in the west and a sun set in the east. And speaking of rotation, one day on Venus lasts a long time. 243 Earth days, but it has a comparable shorter year 225 earth days.

It’s a rocky planet, or a terrestrial planet. Venus’ surface is a cratered and volcanic landscape. with a very dense and thick atmosphere. That “air” is primarily carbon dioxide (CO₂) and nitrogen (N₂), with clouds of sulfuric acid (H₂SO₄) droplets. Which is very toxic to most things that we consider living.

Venus is pretty ordinary. . no moons and no rings. But HOT! It gets temperatures of almost 480 degrees Celsius (900 degrees Fahrenheit) Which is too hot for life as we know it.

It’s a cruel harsh world of dim light, super heated air from run away greenhouse effect and toxic air. The super heated world has temperatures hot enough to melt lead. Images taken below the clouds reveal volcanoes and deformed mountains. Unfortunately, the planet is so hot that probes make it down and take a few images before shutting down due to the extreme heat rendering the probes useless.

Venus has a small magnetic field which was discovered in 1967, by Venera 4. The Magnetic field is much weaker than earth’s and is induced by an interaction between the ionosphere and the solar wind. This is a bit different than say Earth’s which is produced by the internal dynamo in the core. Venus’s small induced magnetosphere provides negligible protection to the atmosphere against cosmic radiation. This radiation may result in cloud-to-cloud lightning discharges.

The weak magnetosphere around Venus means that the solar wind is interacting directly with its outer atmosphere. Here, ions of hydrogen and oxygen are being created by the dissociation of neutral molecules from ultraviolet radiation. The solar wind then supplies energy that gives some of these ions sufficient velocity to escape Venus’s gravity field. This erosion process results in a steady loss of low-mass hydrogen, helium, and oxygen ions, whereas higher-mass molecules, such as carbon dioxide, are more likely to be retained. Atmospheric erosion by the solar wind probably led to the loss of most of Venus’s water during the first billion years after it formed. The erosion has increased the ratio of higher-mass deuterium to lower-mass hydrogen in the upper atmosphere by 150 times compared to the ratio in the lower atmosphere.^[1]

Photographing

Venus in a 6″ Celestron SCT

I was only able to get one photo. It’s a tough planet to get, Mercury is just as tough for several reasons. First off you can’t get a full image due to it being inside the orbit of earth. As explained in the next image:

The phases of Venus : Image credit http://www.physast.uga.edu/~rls/astro1020/ch3/ovhd.html

Earth looks very similar if viewed from Mars, for the same reasons. I didn’t really enjoy photoing this planet, it’s only visibly low in the horizon at either sunset or sunrise, due to it’s location in the solar system nearer the sun. This makes it a very small window to get the images. Mercury is even harder. I don’t think I’ll revisit this due to my current location and there being an abundant of trees. But hey at least now I can say I saw it.

I only recall I used the Celestron 6se and the Orion StarShoot Deep Space Video Camera II, I hadn’t purchased the neximager5 which I think might be interesting to try it with. I don’t recall the settings as I hadn’t started logging notes just yet.  This is the very reason and my chase of Jupiter that caused me to start logging notes. I couldn’t remember the settings I had used and as I jumped from planets to stars to dso’s I would forget the settings. I’ve used them so much now I remember what to use when. I was also not as good with Registax as I am now and as versed in capturing images with the cameras. It might be worth the look with the neximager5, I just didn’t enjoy this planet as much, it’s just a real hassle to me. Some astronomers enjoy chasing it and seeing what phases they can get.

Data

Discovered By		Known by the Ancients
Date of Discovery		Unknown
Orbit Size Around Sun (semi-major axis)		Metric: 108,209,475 km English: 67,238,251 miles Scientific Notation: 1.0820948 x 108 km (7.2333566 x 10-1 A.U.) By Comparison: 0.723 x Earth
Perihelion (closest)		Metric: 107,476,170 km English: 66,782,596 miles Scientific Notation: 1.07476 x 108 km (7.184 x 10-1 A.U.) By Comparison: 0.731 x Earth
Aphelion (farthest)		Metric: 108,942,780 km English: 67,693,905 miles Scientific Notation: 1.08943 x 108 km (0.7282 A.U.) By Comparison: 0.716 x Earth
Sidereal Orbit Period (Length of Year)		0.61519726 Earth years 224.70 Earth days By Comparison: 0.615 x Earth
Orbit Circumference		Metric: 679,892,378 km English: 422,465,538 miles Scientific Notation: 6.799 x 108 km By Comparison: 0.723 x Earth
Average Orbit Velocity		Metric: 126,074 km/h English: 78,339 mph Scientific Notation: 3.5020 x 104 m/s By Comparison: 1.176 x Earth
Orbit Eccentricity		0.00677672 By Comparison: 0.406 x Earth
Orbit Inclination		3.39 degrees
Equatorial Inclination to Orbit		177.3 degrees (retrograde rotation) By Comparison: 7.56 x Earth
Mean Radius		Metric: 6,051.8 km English: 3,760.4 miles Scientific Notation: 6.0518 x 103 km By Comparison: 0.9499 x Earth
Equatorial Circumference		Metric: 38,024.6 km English: 23,627.4 miles Scientific Notation: 3.80246 x 104 km By Comparison: 0.9499 x Earth’s
Volume		Metric: 928,415,345,893 km3 English: 222,738,686,740 mi3 Scientific Notation: 9.28415 x 1011 km3 By Comparison: 0.857 x Earth’s
Mass		Metric: 4,867,320,000,000,000,000,000,000 kg Scientific Notation: 4.8673 x 1024 kg By Comparison: 0.815 x Earth
Density		Metric: 5.243 g/cm3 By Comparison: Comparable to the average density of the Earth.
Surface Area		Metric: 460,234,317 km2 English: 177,697,463 square miles Scientific Notation: 4.6023 x 108 km2 By Comparison: 0.902 x Earth
Surface Gravity		Metric: 8.87 m/s2 English: 29.1 ft/s2 By Comparison: If you weigh 100 pounds on Earth, you would weigh 91 pounds on Venus.
Escape Velocity		Metric: 37,296 km/h English: 23,175 mph Scientific Notation: 1.036 x 104 m/s By Comparison: 0.926 x Earth
Sidereal Rotation Period (Length of Day)		-243.018 Earth days (retrograde) -5832.4 hours (retrograde) By Comparison: 243.68 x Earth
Minimum/Maximum Surface Temperature		Metric: 462 °C English: 864 °F Scientific Notation: 735 K

Atmosphere
Surface pressure	92 bar (9.2 MPa)
Composition	≈ 96.5% carbon dioxide ≈ 3.5% nitrogen 0.015% sulfur dioxide 0.007% argon 0.002% water vapour 0.0017% carbon monoxide 0.0012% helium 0.0007% neon trace carbonyl sulfide trace hydrogen chloride trace hydrogen fluoride

Referances:

1.) Svedhem, Håkan; Titov, Dmitry V.; Taylor, Fredric W.; Witasse, Olivier (November 2007). “Venus as a more Earth-like planet”. Nature 450 (7170): 629–632. Bibcode:2007Natur.450..629S. doi:10.1038/nature06432. PMID 18046393.

2.) NASA: http://solarsystem.nasa.gov/planets/profile.cfm?Object=Venus&Display=Facts

 

 

Transit of Venus

Sadly, the transit of Venus is something I will not see again in my life time. It’s orbit and speed is such that it has 2 close transits then a long one.  I doubt anyone reading this will be alive by the time we have another one. . HOWEVER I am a very thorough individual and like to see things through. . who knows right? Transits of Venus have intervals of 8, 121.5, 8 and 105.5 years. Unfortunately as much as I would have loved to come up with this table. . .I can’t have done anything new with it and have to give credit to whom did.

                                     Transits of Venus: 1601-2400

        Date       Universal    Separation     
                    Time     (Sun and Venus)

     1631 Dec 07     05:19         940"
     1639 Dec 04     18:25         522"
     1761 Jun 06     05:19         573"
     1769 Jun 03     22:25         608"
     1874 Dec 09     04:05         832"
     1882 Dec 06     17:06         634"
     2004 Jun 08     08:19         627"
     2012 Jun 06     01:28         553"
     2117 Dec 11     02:48         724"
     2125 Dec 08     16:01         733"
     2247 Jun 11     11:30         693"
     2255 Jun 09     04:36         492"
     2360 Dec 13     01:40         628"
     2368 Dec 10     14:43         835"

Acknowledgments

Transit predictions were generated on a Macintosh G4 iBook using algorithms developed from the Explanatory Supplement [1974] and Meeus [1989].

All calculations and diagrams presented in here are those of the author and he assumes full responsibility for their accuracy. Permission is freely granted to reproduce this data when accompanied by an acknowledgment:

“Transit Predictions by Fred Espenak, NASA/GSFC”