Space Part 1: Our Solar System: Venus

I apologize for not posting these past few days.  Been busy with travelling and seeing some friends.

Continuing with my series on the Solar System, its time to examine the planet Venus.

Venus:

Venus is the second planet from the Sun, 67 million miles away from our star (about 8,500 Earths).  Venus is often referred to as Earth's sister planet, due to the fact that Venus' diameter is only about 400 miles less than that of Earth's.

Just about the same size.

Despite the fact that Venus also has a similar density and geological makeup to the Earth, the similarities stop there.  The image above is a radar image of the surface of Venus, showing the geological features and the color of the planet's surface.  The truth is, before the Magellan mission in 1989 which mapped 98% of the planet, scientists had very poor images of the surface of Venus.  Here is the first image ever taken of the surface of Venus:

Photo taken by the Venera 13 space probe.

As impressive as it is to take a picture from the surface of Venus, one kind of wishes that the USSR could have at least had the camera face up.  One thing that the Soviets could do right though was measure the temperature of the surface and what the atmosphere was made of.  The surface of Venus is on average about 900 degrees F, plenty hot enough to melt lead.  Why though, if Venus is similar in size and composition to the Earth, should they have such drastic differences in temperature?  The answer is kind of complicated but very cool.  Billions of years ago, scientists believe that Venus may have had an atmosphere similar to that of Earth's and may have supported oceans of liquid water.  There is no direct evidence that water has been on the surface of Venus for the past billion years.  However, scientists do believe that it used to exist, in part because there is still some water vapor in the atmosphere.  However, because of its proximity to the Sun, Venus was rapidly losing hydrogen to space due to the powerful solar winds.  This eventually caused the surface temperature to rise and made the oceans boil off.  Here is where it gets really crazy.  Scientists are not sure exactly what happened, but something catastrophic happened to Venus about 700 million years ago.  Scientists disagree heavily as to the actual cause, but there is no arguing that about 700 million years ago, massive amounts of volcanic activity all across the surface of the planet began to take place.  Currently, 80% of the surface is covered by cooled off lava flows.  This dramatic shift in the history of Venus basically resurfaced the planet.  All across the surface, scientists determined that the age of the rocks is about 700 million years; young by geological standards.  This period of vulcanism spewed massive amounts of sulfur and carbon dioxide into the atmosphere, giving Venus its heavy and dense atmosphere.

As this image shows, the Venusian atmosphere is made almost entirely of sulfuric acid and carbon dioxide.  The dense and acidic nature of the atmosphere destroys most things that fall through it, but as if that wasn't dangerous enough, the atmosphere of Venus is theorized to be inundated with lightning strikes.  In addition to these horrifying conditions, the sheer mass of the atmosphere is 92 times that on Earth, about the same pressure as being 1 km below the surface of the ocean.  Any probe sent to the surface of Venus has been destroyed within a matter of weeks.

A picture taken of Venus by the Pioneer space probe.  Notice the extremely dense atmosphere.

Despite these crippling condition on the planet, there is still an immense amount of scientific research conducted because of the information that Venus can give us about Earth.  The thick atmosphere of Venus has been dubbed as a runaway greenhouse effect, meaning that if we can understand how Venus works, maybe we could use that information to help the Earth and its changing climate.

On a more excellent note, Venus is one of the brightest objects in the night sky due in part to its thick atmosphere.  On a very clear night, Venus appears to almost have a halo of haze surrounding it caused by its dense atmosphere.  This year in particular, one of the most intriguing astronomical events wil take place, the transit of Venus.  This is when Venus will pass in front of the Sun, casting a dark spot to appear on the surface that can be seen from Earth!  This only only happens twice every 125 years and these two times happen within close proximity to each other.  The last time this happened was in 2004 so this years is the last time it will happen in our lifetime.

The light grey areas are where the Transit will be visible.

As the image shows, on June 5, 2012, the transit of Venus will be visible from North America at right about sunset.  On June 6, 2012, half of Africa, Asia, and Australia will get a view.  Don't miss this once in a lifetime opportunity.

Here is a picture of the 2004 transit of Venus (Venus is the black dot in case you didn't get that part).

I hope you enjoyed this entry, more to come on the solar system!  By the way, looking directly at the sun without eye protection can cause serious damage to your eyes.

Here are a few useful links:
Some cheap glasses to safely look at the sun
Transit of Venus website