Over the years we have discovered many exoplanets of any size, temperature, surface, etc. But how to astronomers do this? How do you find an exoplanet? These planets are very small and faint, that is why it is hard to see them from the Earth, and we have to use other methods of observation. One of the most popular methods is called ‘transit method”. Astronomers measure the brightness of a star for a very long period of time to look for periodic decreases in its brightness when a planet might be passing it.
Not long ago, NASA announced the discovery of a system of exoplanets orbiting a single star in the constellation Aquarius. The system is called Trappist-1 and contains 7 extrasolar planets.
Six of the planets in Trappist-1 lie in a zone where the temperatures of the surface range from 0°C to 100°C. Three of the planets might have oceans which increases the chances of life to occur.
The pioneer monkey in space was named Albert II. On his mission, he made it 83 miles above the Earth. However, despite surviving the trip up, Albert II died when his parachute malfunctioned on his way down. On his trip, he was under anesthesia, and attached to sensors so that scientists could monitor his vitals and the amount of radiation he experienced during his journey.
While Albert I died before takeoff, the first monkeys to survive the journey into space were Able and Miss Baker, flying 360 miles into space. Both monkeys survived the flight and their trip gave us much information for future journeys.
In 1972, NASA launched the Pioneer 10 spacecraft with Jupiter as the primary target. After sending back data from this giant world, Pioneer 10 became the first spacecraft to leave our Solar System. NASA received the last, very weak signal from Pioneer 10 in 2003, so as far as we know, Pioneer 10 is still heading towards Aldebaran, located in the constellation Taurus. While unlikely that Pioneer 10 will reach another civilization, NASA (mainly Carl Sagan and Frank Drake) provided Pioneer 10 with a plaque that would hopefully tell another intelligent civilization about our own civilization on Earth.
At the top of the plaque, the two connected circles represent two hydrogen atoms. When hydrogen atoms change energy states, electromagnetic radiation is released, the wavelength of which is about 21 centimeters and the period of which is about 0.7 nanoseconds. Thus the hydrogen atoms provide a standard unit of spatial and temporal measurement. The small tick between the atoms assigns these values of distance and time to the binary 1.
Below the hydrogen atoms is the representation of our cosmic address. At the center of all the lines is the Sun and each radial line signifies the relative distances and directions to known pulsars. Each line has a binary number stating the period of the pulsar. This pulsar map would tell another space-faring civilization both where we are and what time we drew the image. At the very bottom of the plaque is a drawing of our solar system, including just the Sun and the (at the time) 9 planets. Each planet has a binary number telling its distance from the Sun. The arrow and mini pioneer drawing show the path of the spacecraft out of our Solar System.
The final image on the right depicts a man and a woman standing in front of the pioneer spacecraft. The man is holding up an open palm, Earth’s universal greeting. The woman stands with arms down and her weight shifted to show that humans are mobile and flexible. Next to the woman is the binary number 8, with two other ticks indicating this number represents her height. Another civilization could then calculate that the woman is about 5 1/2 feet tall, and use her size to judge the relative sizes of the man and the pioneer spacecraft.
While it is unlikely that any other civilization will find Pioneer 10, it is still fascinating to think that if another civilization did find it, they would be able to discover who we are and where we live in the galaxy. It is also interesting to note that every level of the hierarchy at NASA was all for the idea of giving Pioneer 10 a message for alien races.
Extrasolar planets are a recent discovery in the time of our Universe. So far, there are 3,475 confirmed exoplanets. These planets are most often comparable to the gas and ice giants that we have in our Solar System.
However, there is a constant search for planets that are similar to ours: in the habitable zone around their respective star. A breakthrough came, just yesterday, April 26, 2017, with the discovery of an Earth-sized iceball planet. Scientists found this planet using telescopes in two different locations, allowing different vantage points for observations. While this planet is likely too cold for life, it can give insight into the formation of different types of planets. More observation is needed to know about this planet and its star in order to determine what type of star the planet is orbiting. There is a possibility that the star that the planet is orbiting is not a star at all, and that it is something that does not have enough heat to have nuclear fusion.
The Arecibo Observatory was constructed in 1963 as the world’s largest and most sensitive radio telescope. Sitting in a naturally spherical valley in Puerto Rico, this telescope looks decidedly different from the pristine optics associated with optical telescopes such as the Keck Observatory or the Hubble Space Telescope. This is because the Arecibo Observatory peers into the Universe with radio waves. These radio waves have large wavelengths, between 3 cm and 1 meter, so the green vegetation stains on the bottom hardly make a difference. In fact, the radio dish isn’t even a smooth round shape; the spherical dish is comprised of 38,778 suspended flat steel plates that approximate the spherical shape used to concentrate radio signals to the moving receiver and transmitter suspended above the dish by three cables.
The unique transmitting feature of the Arecibo Observatory was put to use in 1974, when at the behest of Dr. Frank Drake (author of the Drake equation) and Carl Sagan, a binary message was sent towards the star cluster Messier 13. This message (more information here) contains information about life on Earth, human biology, our place in the solar system, and current Earth technologies. If we are lucky (or potentially unlucky), aliens should be able to pick up this signal from M13 within about 25,000 years, when the light speed signal reaches these distant stars. Now we Earthlings have to patiently wait around 50,000 years for a potential return signal, but in the meantime, the Arecibo Observatory has been busy making radar mappings of the surface of Venus, finding Soviet radar stations by observing radio waves reflected from the Moon, and generally advancing our knowledge of the Universe.
The idea of life in other star systems has long intrigued mankind. However, it is likely that before life can be identified we must discover the planets upon which this life would spawn. Within the star system TRAPPIST-1, seven Earth-sized planets have been discovered, three of which are within the star’s habitable zone. The star is 40 light years away, which is closer than many stars but still farther than humans currently have the capability of reaching by physical means. So how did we find all these planets?
This is an artist’s conception of what the planetary system TRAPPIST-1 might look like from the NASA website.
The planets were all located by transit, which is a method used by astronomers that tracks the brightness of a star over time. Therefore, when a planet or planets cross in the path of the sun (in relation to Earth) then the visible brightness of the star decreases. The difference in visible light is unnoticeable to the human eye, but telescopes can detect differences of as little as one hundredth of a percent of the total light given off by a star. Across time a graph is formed that shows transits as dips in the star’s brightness. Once a planet can be identified by its transit three times, it is confirmed to exist.
The planets in the TRAPPIST-1 system were relatively small, so without their frequent orbits, it would have been incredibly difficult to learn of their existence. Transit identification methods favor planets that are large and that have quick orbital periods. Large planets block more light, thereby making their transits more noticeable. A faster, shorter orbit means that the planet transits more often, making it easier to identify the pattern and track it across multiple revolutions.
Now that we know the TRAPPIST-1 system holds good chances of life, it will be exciting to see what else we are able to discover about the planets.
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:
We are the only galactic civilization and alone in the universe
Galactic civilizations are scattered about the galaxy, but no one has colonized it.
Interstellar travel is more difficult than we anticipated and societies are bound to their solar system
Human curiosity to explore is an uncommon trait
Civilizations are unable to handle their technology and end up destroying themselves before they are able to colonize.
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?
In the last year or two, you may have heard the term ‘SpaceX’ pop up in casual conversation. You may have then asked yourself questions like “what is that?” or “who are they?” or “Is this another government moon landing conspiracy?”. Well, if you have, then I am here to briefly tell you exactly who they are, what they do, and why you should care.
First things first: Elon Musk. This man is a superhuman. Currently the CEO of not only SpaceX but also Tesla and Neuralink, as well as a leader in various other pioneering technology companies, this man does it all. If you want to know where advancements in technology are headed in the near future keep an eye on this guy. Anyways, his goal for the company SpaceX is simple: reduce the cost of space travel enough to enable the colonization of Mars. He believes this is achievable in either year 2024 or 2027.
How does SpaceX make money to fund such an ambitious project? Good question. They do so largely through an ISS (International Space Station) resupply contract with NASA, as well as contracts with the department of defense and other commercial companies for which they send satellites into space. All the while they are constantly improving their launch techniques and reducing costs. Just last month they completed the first relaunch and landing of a used orbital rocket. This is incredibly important because the orbital rocket is the largest and most expensive component of a space craft, and to make it reusable brings us all much closer to an affordable ticket to Mars.
All in all, SpaceX is one of the most exciting companies in the world right now. They have extremely ambitious goals and are already making history at an alarming rate. If you ask me, we’ll be putting a man on Mars very soon. Watch the video below to see their vision in color:
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
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The Drake Equation can be used to estimate the number of communicating civilizations in the milky way galaxy. First proposed by astronomer Frank Drake in 1961, the equation uses a series of variables to calculate the number of communicating civilizations, N. The variables each represent some cosmic parameter (mostly fractions) that influences the likelihood of existing civilizations (see below).
While some of these parameters are pretty well defined, many are up to the discretion and imagination of the scientist. For example, the number entered for the variable L can make a huge difference in the final number. An optimist who might believe that humans will last for millions of years will input a much, much larger number than someone who enters a number reflecting that the human race is past the halfway point. Either number is a fine choice–it is pure speculation. Therefore this equation, although interesting, cannot be taken as an accurate predictor for possible life within our galaxy.
