It’s not easy being green.
Just ask Venus.
Hello!
I’m Ian O’Neill, space producer for Discovery News, and I thought I’d pop into the studio
today to talk about a planet that rarely gets much press, even though it’s considered
Earth’s evil twin.
I am of course talking about Venus -- a world that’s closer to the Sun than Earth is,
but has an environment that is EXTREMELY hazardous to life.
Well, for LIFE AS WE KNOW IT, anyhow.
(There might be little cloud-floating aliens… who knows!
But that’s for a different episode.)
For a long time, Venus remained a tantalizing mystery for astronomers -- the thick hazy
atmosphere completely obscured its surface, keeping it a well guarded secret.
But after decades of observations by telescopes on the ground, unmanned spacecraft flybys,
plus a Soviet lander and balloon-borne atmospheric probe (yes, we’ve floated a balloon in the
atmosphere of another planet!), we’ve come to realize that Venus is a deeply fascinating
place.
But we won’t see astronauts exploring its surface any time soon -- because, ya know,
they’d MELT.
So we tend to focus more attention on Earth’s red sibling, Mars.
Now that the European Space Agency has the Venus Express satellite in orbit around Venus,
there’s been a lot more interest in the clouded planet and the mysteries its atmosphere
contains -- and one of the most mysterious things about Venus is its green glow.
On Earth, we have the aurora -- also known as the Northern, or Southern Lights.
When seen by the naked eye, we see predominantly green light at high altitudes, but the aurora
comes in a whole range of colors.
The aurora happens more frequently during times of high solar activity, so when the
Sun throws a coronal mass ejection, basically a vast magnetized bubble of high energy particles,
in Earth’s direction, our planet’s global magnetic field deflects the particles and
injects them into the Earth’s poles.
The high energy particles, mainly protons and electrons, slam into the high atmosphere,
causing atmospheric gases to generate light.
The green light we often see is oxygen emissions and at the same time we’ll also see a red
emission, that is also oxygen atoms, only at higher altitudes.
But Venus doesn’t have a global magnetosphere like Earth, so for the past 40 years, astronomers
have been trying to understand whether or not Venus can even have auroral activity.
Using a high resolution spectrometer attached to the 3.5-meter telescope at Apache Point
Observatory in New Mexico, researchers were able to spot green emissions from the Venusian
ionosphere when coronal mass ejections slammed into the planet.
However, these emissions were more diffuse all over the Sun-facing side of the planet
as there is no magnetosphere to concentrate the high-energy particles at the poles, like
Earth.
Also, there was no sign of red aurora activity at high altitudes.
Now they are trying to understand what chemical reaction is causing this green glow; is it
the small quantities of molecular oxygen in the atmosphere, or is something else going
on?
More Earth-based observations and help from Mars Express are needed.
This is an exciting result as we are beginning to understand how space weather impacts planets
without global magnetic fields, including Mars.
All in a day’s work for our space weather forecasters...
Do you have any wild theories to explain why Venus produces this green glow?
Let us know in the comments below and please subscribe for more DNews every day of
the week.