Hi everyone I'm Darrell Heath with the UALR College of Arts, Letters and Sciences.
Welcome to The Night Sky . When I was a boy of about 10 or 11 I became
hooked on Edgar Rice Burroughs as John Carter of Mars novels. For weeks on end I
stuffed my head on these planetary science fiction adventures. And craving
more, I then turned to his Carson of Venus novels. Yeah, Burroughs had a
tendency to recycle his plots but I didn't care. I just wanted more wild
adventure stories that took place on other planets. And whereas his version of
Mars was that of a dry and dying world inhabited by an assortment of exotic
aliens and creatures, his Venus was that of a tropical paradise. According to
Burroughs, Venus was a planet and shrouded by water laden clouds and
beneath those clouds was a world that was mostly ocean with a few land masses
covered in jungle. What's more there were giant reptiles a plenty. And for a boy
who was also in love with dinosaurs, Venus seemed like the place for me.
On paper Venus and Earth do appear to be twin sisters of one another. Both are
very similar in size and mass with Venus being just a bit smaller. Both have a
similar surface gravity and both possess substantial atmospheres and
even clouds. But there the similarities end. As most of you already know the
planet named for the Godess of Love is downright nasty. Orbiting spacecraft
using ground-penetrating radar as well as probes sent to the surface reveals a
world more akin to hell than paradise. Venus's surface temperature is a
scorching 860 degrees Fahrenheit. That's hot enough to melt lead.
The atmosphere is so thick that were you able to reach the service
you would be crushed under a pressure that's over 90 times what you experience
here on Earth. The Venusian atmosphere is mostly carbon dioxide.
And those clouds that perpetually enshroud the planet are
not made of water vapor but instead composed of sulfuric acid. No oceans of
liquid water cover Venus. It's surface is a desolate landscape of scorched rock
and thousands of dormant volcanoes. But was Venus always this way? And if not then
what made it so inhospitable? Many astronomers believe that during the
first two billion years of its history Venus may well have contained oceans of
liquid water. In fact it was this water that eventually led to the planet
becoming the hellish world we know today. But the instigator from the transition
from paradise to hell wasn't the planet itself but the Sun. Like any star, our Sun
has undergone changes during its 4.5 billion year history. And will undergo
more changes in the distant future. Early on in its life the Sun was much dimmer
and cooler than it is today. And during this time Venus was on the edge of the
habitable zone at around 67 million miles away from the Sun. But at around
2.5 billion years ago, the Sun began to brighten... become much warmer. Being much
closer than the Earth is to the Sun, Venus began to warm up and its water
began to evaporate to form a thick cloud layer that enshrouded the planet. Now water
vapor is a potent greenhouse gas. So while sunlight was allowed to penetrate
the cloud layer, the much longer wavelengths of infrared heat energy was
prevented from escaping. This made Venus even hotter and even more water vapor
entered the atmosphere. The result was a runaway greenhouse effect. Eventually the
surface became so hot that carbon was baked out of the rocks which then
entered the atmosphere to create carbon dioxide... another powerful greenhouse gas.
Venus's fate was sealed. And all the water on the surface boiled away.
Today, we can find only traces of water in the atmosphere the rest has escaped out into space.
In a surprise twist space probes have discovered that at about 31 to 40
miles above the surface there exist conditions that a
the Earth like. In fact you'll not find such hospitable conditions anywhere else
in the solar system. At these altitudes the atmosphere is actually breathable
with a mixture of 21 percent oxygen and 78 percent nitrogen.
But if you plan to visit be sure and bring along the air conditioner
because temperatures are at around 167 degrees Fahrenheit. While human-induced
global warming will most likely not create conditions as extreme as those on
Venus, the planet still serves as a stark reminder of the dangers of dumping
excess greenhouse gasses into our own atmosphere. Even a fraction of those
conditions experienced on Venus will have devastating consequences for life
on Earth. Now whenever Venus is visible in our morning or evening sky it's often
the brightest object visible outside of the moon. All this month you can spot the
second planet from the Sun quite easily during the hours of dusk just around
after sunset... low along the western horizon. Be sure and look for the much
fainter planet Mars next to it. Early on the month Mars will be at about eight
degrees above Venus but as the month wears on they'll get closer and closer
together. On the nights of February 20th through the 23rd the two are less than
one degree apart. A close pairing indeed. On the 21st they're actually a half a
degree apart. And once more we will have a very lovely crescent moon that will be
part of the western sky view as well. When Venus and Mars are that close
you'll either need binoculars or small telescope to split them apart optically.
Now keep in mind that even though they are close together on the sky they are
in fact separated by millions of miles in space. That's all for now. But be sure
and visit our website for more astronomy news and information. Until next time be
sure and get outside to look up and wonder.