Take Me To Your Leader

 

 

In 1950, Enrico Fermi famously asked: “Where is everybody?” With humanity’s rise in technological progress, we could colonize the galaxy within a couple million years. If we apply the Cosmological Principle (We are not special) to our galaxy, the cosmos should be crawling with life. With over half a trillion planets in our galaxy and the notion that planetary societies are not rare, we should have run into a galactic civilization by now. Fermi wondered why we have no evidence fir life outside of Earth and offered his paradoxical idea. Fermi’s has at least ten solutions (see picture above), though they can be condensed into three broad categories:

  1. We are the only galactic civilization and alone in the universe
  2. Galactic civilizations are scattered about the galaxy, but no one has colonized it.
    1. Interstellar travel is more difficult than we anticipated and societies are bound to their solar system
    2. Human curiosity to explore is an uncommon trait
    3. Civilizations are unable to handle their technology and end up destroying themselves before they are able to colonize.
  3. There is a galactic civilization that has indeed colonized the galaxy but has not revealed itself to us.

Regardless of the solution, the paradox has two distinct outcomes: We are alone in the universe or there are other out there. Both of these answers are terrifying and hard for most people to accept. In a way, the next step relays on our future. Will we destroy our race and planet or will we rise above and take the first step in colonizing the galaxy?

Source: Cosmic Perspective: Chapter 24

Not Too Hot, Not Too Cold

 

The ¿habitable zone¿ (shown in green) is a term astronomers use when searching for exoplanets that could be possible hosts to alien life. Also known as the ¿Golidlocks zone¿, the term refers to a planet that sits the perfect distance from its host star for liquid water to exist on the surface

The ‘Goldilocks’ zone. More information here: Article

 

Earth is the only planet in our universe that we currently know supports life. For a planet to harbor life as we know it, it must lie in a star’s habitable zone. Being positioned in the zone is not enough, however. Countless planets orbit their suns at the proper distance and do not have life, including the planet Mars in our solar system. Why is the habitable zone so important for life? The so-called “Goldilocks zone” sits far enough away from a star that it does not experience intense heat, yet close enough that it does not reach extreme cold. This perfect distance allows water to condense as rain and form liquid oceans. As we know how fundamental water is to life, it is hard to know whether life could exist without it. Since our planet is our only sample size, it is a safe bet to search for life in areas we know they can thrive.

The Habitable zone varies on the size of the star. Stars with solar masses less than our Sun will have habitable zones much closer to the star since it has lower mass and luminosity. Likewise, a giant star has a habitable zone further than the Earth’s position. If a massive star existed in the Sun’s place, its high brightness and mass would radiate heat scorching Earth and warming Jupiter and Saturn to moderate temperatures.

Source: The Cosmic Perspective: Chapter 24

Chaotic Earth

Earth’s violent past: GIF

From Earth’s birth 4.6 billion years ago, it has been through some violent trauma. From worldwide ice ages and raging fire storms, it is a wonder that we made it here in one piece….or most of us. Asteroids regularly come in contact with Earth, wreaking havoc on the surface below. These meteors interfere with nature’s evolutionary course and artificially choose which species are most “fit” for their environment. A meteor may have given humanity our big break, allowing us to evolve into a more intelligent species. Had this mass extinction never occurred, dinosaurs would likely still be roaming the Earth today.

An alternate theory of the mass extinction

Current scientists believe that a massive asteroid struck Earth 65 million years ago. The meteor came in at an angle, raining fire across the continents. After striking the Earth, a massive tsunami struck most of the land-dwellers down. The dust that was spread throughout the atmosphere had the deadliest effects: global winter. Those species that didn’t suffocate in the smoke or freeze in the suddenly cool climate, starved, as photosynthesis halted for a year. This mass extinction killed 99% of the creatures living on Earth and eradicated 3 quarters of the terrestrial species. Those that could burrow deep in the group or swim to the bottom of the ocean stood a chance at survival, everyone else perished. The most successful creatures to survive this extinction were small mammals who hid under the earth and stored food before the disaster. Now, birds are the only memories of the giants that once ruled the Earth.

Source: Cosmic Perspective Chapter 12

Life On Other Worlds

Image result for exoplanets

An artist’s rendition of a habitable world: IAU

The search for exoplanets is one of the most exciting projects in science today. The possibility of earth-like worlds harboring intelligent life is what has electrified most science fiction geeks. With enough funding, the possibilities are endless! Our ability to detect these elusive worlds has improved since our first discovery two decades ago. In late ’95, astrophysicists found a planet the size of Jupiter orbiting a star elsewhere in the Milky Way. It wasn’t long before astronomers rushed to the occasion and began vigorously scouring the skies for these fascinating worlds.

The new field of astrobiology has been born out of the exoplanet search. If we find new worlds, we must find out if there is a possibility of life on its surface. So far, astrobiologists have gotten their hands dirty by analyzing ancient meteorites and examining extremophiles, organisms that thrive in some of the most extreme conditions from volcanoes to the depths of the ocean floor.

The most popular method of finding these extrasolar planets is the transit method. This technique uses the spectrum of a star and detects a planet if a portion of its light decreases temporarily in a pattern. The planets are going through its elliptical orbit and with each cycle, it passes around its Sun, blocking part of the light from our view. It is exciting that we are living in a time where if life exists out there, we will most likely know soon!

Here is an informative exoplanet video!

Sources: Cosmic Perspective: Chapter 13, nature.com

The Terrestrial Worlds

Source: Here

The planets of the Solar System dramatically vary from massive gaseous, ringed giants to
miniature rocky terrestrials. The celestial bodies are also at such great distances that no map of our Solar System can truly illustrate both the distances and relative sizes to scale. The terrestrial planets are relatively similar in size and composition, but interestingly, their atmospheres could not be more different.

Cool Solar System Scale Video!

Atmospheres are vital to the survival of life,  though they do not normally extend very far past the planet’s surface. Our atmosphere is about as thick to the Earth and the thickness of a piece of paper is to a globe.

Mercury, the smallest and lightest planet and nearest to the Sun, has virtually no atmosphere. This means that the stars would be visible through the daytime. With a lack of a serious atmosphere, Mercury is unable to retain its heat, despite its close proximity to the Sun. Unfortunately for Mercury, the planet is vulnerable to heavy cratering and has the appearance of our Moon. Mercury’s days are longer than its year, leading to extreme temperature fluctuations.

Venus is the next terrestrial world, similar in size to the Earth. It is one of the brightest objects in our Solar System, known as the morning and evening star. Its atmospheric pressure is 92 times higher than Earth and Venus’s hellish Greenhouse effect has created a wasteland. Despite not being the closest planet to the Sun, Venus has heated itself beyond belief. Venus serves as a stark reminder of the destructive power of the greenhouse effect.

Our home, Earth, is the largest terrestrial planet and has a powerful ozone layer to protect us from dangerous light and has temperatures that tolerate life and allow for liquid water. Its combination of water and CO2 provide a greenhouse effect that is just strong enough to keep our planet warm. Unlike the other terrestrials, the Earth’s surface is rich and diverse. It also has a Moon that is oddly large in comparison to the size of the Earth.

Mars is the second smallest planet and fourth terrestrial from the Sun. Its mass is just one-tenth of Earth’s. Its atmosphere is incredibly thin and exposes the planet to harmful radiation. It has polar ice caps at its poles, made from frozen CO2 and is the only world that might have once supported life. Its surface also experiences violent dust storms that can last for months, blocking the planet’s surface from view.

Examining the differences between the terrestrial planets’ atmospheres is just another reason why we are so lucky living on Earth. A perfect balance between the scorching Venus atmosphere and Mercury’s lack of one, the Earth provides the perfect home for life.

Sources: Cosmic Perspective: (195-198, 271-272), Planetary Atmospheres Article

The Earth’s Gravity

 

Gravity on Earth acts on all objects with the same force. No matter their mass, objects fall and accelerate at a constant rate. Due to the air resistance of different shapes, this is not always apparent. On a planet or moon lacking oxygen, the law could be simpler to demonstrate. On Earth, falling objects increase speed by 9.8 meters per second. Though gravity is a constant, there are places on earth where gravity has less of an effect than the familiar force. On the top of Mount Everest, you would experience 0.28% less of the gravitational force than at around sea level, though this is almost unnoticeable.  You can read more about gravity here.

In 1589, Galileo publicly demonstrated the gravitational acceleration on objects of different masses  by dropping a heavy and light cannon ball simultaneously.  The larger one was ten times heavier, though each object smashed into the ground at about the same time. Due to the air, their falls were not perfectly equal in speed. The experiment helped disprove Aristotle’s argument that bodies ten times larger should fall ten times faster.

Super awesome Galileo gravity experiment in vacuum chamber Here

2017 Solar Eclipse

rt_solar_eclipse_01_jef_160308_31x13_1600Visible solar eclipses are relatively rare phenomenon to witness. They occur whenever the moon gets between the Sun and the Earth. The eclipse must occur with a new Moon to completely blot out the Sun. Because the Moon must be in the right location and phase, these eclipses don’t happen very often. There are three types of solar eclipses. The total solar eclipse is the most impressive occurrence with the Moon gradually covering up the daytime Sun. Temperatures fall and creatures prepare for nighttime. Once the moon completely covers up the Sun, only the surrounding light from the Sun is visible: the corona. This period is called totality. There are also more common annular and partial solar eclipses, where the Moon only slightly blocks the Sun, depending on its position relative to Earth’s umbra shadow.

Luckily, since the Sun is 400 times larger than the Moon and the Moon is 400 times closer, the two objects appear to be the same size. Unfortunately, the Moon is moving about four centimeters away from Earth a year, so this will not always be the case. The next total solar eclipse visible in the U.S. will be on August 21st of this year. It has been 72 years since the last eclipse achieved totality in the United States.

Click HERE for more details and for safety viewing the eclipse.

Totality Video