Space Part 1: Our Solar System: Mars

So here we are.  The end of the inner planets.  By inner planets, I mean the four rocky bodies closest to the sun that lie inside the asteroid belt (next blog topic).

Mars:

Mars is the fourth planet from the Sun.  On average, it is about 140 million miles from the Sun (or about 17,700 planet Earths).  The planet itself has a diameter of 4,196 miles, so just over half the size of Earth.

As you can see, Mars is about twice the size of our Moon but about half the size of the Earth.

Mars is often one of the most easily recognizable objects in the night sky.  This is because of the massive amounts of iron oxide on the surface of the planet.  Despite the iron oxide on the surface of the planet, Mars does not always appear to be red from the Earth.  It often ranges anywhere from yellow, to orange, to red.

Photo of the Martian surface taken by the Spirit rover.

As you can see from the picture, Mars has a barren and rocky surface.  Because of its great distance from the Sun, the temperatures on Mars range from about 23 degrees F to -125 degrees F. This bitterly cold climate is relatively similar to Earth's, in the sense that both planets have seasons.  Due to Mars' distance from the Sun, the seasons last about twice as long as they do here on Earth.  However, despite the fact that both planets have seasons, Earth and Mars have one very key difference: the Earth has a magnetosphere, Mars does not.  Because of this, Mars is not shielded from the solar winds and has not been for the last 4 billion years.  This leaves Mars completely exposed to radiation from the sun, from strikes by meteors, and is the most likely explanation for why Mars no longer has liquid water actively on its surface.

An artist's depiction of the protection that Earth's magnetosphere provides from the solar winds.  And how Mars' (bottom planet) lack of one leaves it completely exposed.

Despite the fact that Mars has not had an atmosphere for billions of years now, liquid water may still in fact exist on the Martian surface.  On April 4th, 2011, NASA released images that very likely could be seasonal water flows on the surface of Mars.  While these images cannot be completely confirmed, scientists believe that these flows are made of very briny water, which would in fact lower its freezing point.

Whatever scientists eventually conclude about these images, one thing that is for certain is that the newest Martian probe will be landing on the surface of the planet this coming August.  Currently, the Martian Rovers Spirit and Opportunity, have been operating on the planet searching for past evidence of liquid water; and they have been very successful.  In August, the Curiosity Rover will be delivered to Mars with four major goals in mind: to study the geology of Mars, study the Martian climate, explore the possibility of future human missions, and answer questions concerning past life on the planet.  Curiosity will offer great insights into many of the most difficult questions concerning Mars.

Finally, as a bit of an afterthought, I feel it necessary to mention a few things about the moons of Mars. Mars is the only other rocky planet besides the Earth to have any Moons, although they are not large enough to be gravitationally shaped into a sphere.  However, both of Mars' moons, Phobos and Deimos, have a chaotic future ahead of them.  Phobos, the larger of the Martian moons, is the closest moon in the solar system to its host planet.  This close proximity to the planet will eventually cause Phobos to either crumble up as it nears the planet, or to directly crash into the surface.  Mars' other moon, Deimos, is on course to no longer be a Martian Moon.  Deimos, like Earth's moon is slowly moving away from its host planet.  Deimos though, unlike our own moon, will eventually be gravitationally slingshotted into the vastness of space, never to be seen or heard from again.

Mars is so intriguing to scientists because there is strong evidence to suggest that the planet may have once supported water and life.  Hopefully, the Curiosity rover will lead to some amazing discovery that changes our perspective on the universe.

Space Part 1: Our Solar System: Earth

Earth:

Earth is the 3rd planet out from the sun; 93 million miles away (11,733 Earths).  Earth is the largest rocky body in our solar system with a diameter of 7,926 miles.  It is also the only known thing in the universe to support life; although many scientists believe that life has to exist elsewhere.  Our planet is dominated by nearly 7 billion human beings; our population is expected to reach 9 billion by 2050.  If we want life to remain on this planet for years to come, we need to get our population under control.

On a happier note, because Earth is our home, it is the most widely studied object in the universe.  Earth was formed about 4.54 billion years ago.  After the formation of the sun, the leftover gases and dust eventually accreted into the spheroid that is our planet.

As this picture shows us, that initial cloud of dust and gases that was our planet eventually came under so much pressure that it ignited, forming our star.  Therefore, the Earth, and all of the living things on it, are here because of the process of star formation.  Our planet, and everything in our solar system, depends on the energy of the sun in some way.

We can also thank the sun for helping the first organisms on this planet get energy.  As mentioned in an earlier blog of mine, some of the first lifeforms on this planet were cyanobacteria (blue-green algae); organisms that thrived off of energy obtained from the sun through the process of photosynthesis.

Some cyanobacteria!

Since those first life forms (whatever they were exactly), life on this planet has gone through some pretty serious ups and downs.  Through the billions of years that life has existed on this planet, there have been countless number of species; including five major extinction events.  It seems as though life has an extraordinary ability to adapt to changing circumstances.  We have found organisms on the bottom of the ocean, underneath the crust at the bottom of the ocean, in the driest deserts, in the freezing arctic, in salt beds, in briny water, and underneath glaciers.  All of these life forms give scientists hope for finding life elsewhere in the solar system and beyond.

Our planet is the one example we have.  It is the one thing we can base our observations off of.  Because of this, it is essential that we develop a greater understanding of the geological processes that control this planet.  In addition, the more we learn about the animals that live on this planet, the more we will understand the complexity of life that might exist in the universe.

However, for all of this to be possible.  We must protect the environment in order to be able to sustain the life that we already know exists here.  There is no point in exploring the rest of the universe if we cannot sustain ourselves on this planet.

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