Asteroid Mining: Effectiveness and Probability

By Ronnie Ovando

Asteroid mining sounds like a notion many people want, but don’t believe will be implemented ever in the near future. After all, anything space travel related sounds like something that costs too much time, labor, and money. However, many people are ambitious and are reaching for the stars (pun intended). Companies such as Planetary Resources state that they have all the resources for this aspiring notion. The question is, are they right?

From my perspective, my biggest concern would be if the ideal conditions for mining are met. Think about it like buying groceries on a budget. The best situation would be if the store was within  walking distance as to save money on gas, and if that particular store gave the best groceries at the lowest prices. Of course, those circumstances are rare and should not be expected nor should be the determining factor. Instead, situations that mimic the ideal conditions should be the deal-breaker in whether one decides to go to that grocery store, or in this case, use asteroids for mining.

RonnieP2F1

“Which are the biggest asteroids?” Graph made from data stored here. Note: LD stances for Lunar Distance (the average Earth-Moon distance)

Assuming that the ideal situation for asteroid mining includes factors such as the size of asteroid and being a voyagable distance to the asteroid, I made two graphs to investigate the size and distance of asteroids in order to find the best candidates for mining. The graphs labeled “Size (meters) v. Next Close Approach Distance (LD)” above and below contain data from the International Astronomical Union’s (IAU for short) Minor Planet Center Website. All the asteroids graphed in the first graph are the Union’s top 20 biggest asteroids. Their sizes range from 5000-46,000 meters. However, none of them made it on to the top 20 list of most travelable asteroids, as shown in the lower graph, despite a handful of them sharing similar distances. I can only assume other elements than distance have an influence on what is considered to be “easy to travel to.”

RonnieP2F2

“Which asteroids are the easiest to travel to?” Graph made from data stored here. Note: LD stances for Lunar Distance (the average Earth-Moon distance)

So this begs the question: is asteroid mining even worth it? One company of the name Planetary Resources says yes. Their CEO, Chris Lewicki, said in an interview for Bloomberg that “The solar system is really an abundance of resources that has enough to power humanity to the end of the sun with a population many thousand times our existing planet.”  Their  website has evolved into a great resource for asteroid mining itself. I was able to find an article that was able to provide information on the concerns I had earlier. Turns out they were the same concerns the company had! Lewicki himself said that the asteroids they target are “Near-Earth.” One of the asteroids of the IAU’s most travelable, 2008 HU4, is one the company is currently interested in.

Distance and size are not the only aspects taken into account. Factors such as change in energy (Delta/△ V), spin rate, and type are used in determining which asteroids are qualified. Size tends to give the most trouble, as the article puts it “Most near-Earth asteroids are much smaller, making the ones large enough a bit harder to come by.” However, the resources gained from asteroid mining could potentially overshadow all the cons. Many asteroids have water in some of form, either as ice or in clay. Appropriate enough, since rocket fuel, you guessed it, is made out of water. Asteroids could act like space versions of the gas stations on Earth.

It’s impossible when talking about asteroids to ignore the different elements found on them and not found on Earth. Platinum is one great example. This element is not found in the earth’s crust, but rather near the core. It is thanks to volcanoes and and asteroid-earth impacts that platinum could be in human hands. Planetary Resources argues that because of the rarity of this metal, economic success could occur if it was mined. Similar to when Andrew Carnegie mass produced steel during the 1800’s, prices for platinum will drop dramatically, making it available for companies to use more and move forward with technology.

Different people informed on this topic will inevitably have different opinions. Some will prioritize short term over long term economics. Others simply care more about the resources such as water and rare metals. Others are preoccupied with the fact that the best asteroids are much farther away. There will be people who question this, and there will be people who work at Planetary Resources. Whatever side you’re on, it’s important to note that space will always be waiting, ready for when we start to travel it.

Habitable Exoplanets

 

by Maddie Meagher

The idea of finding a planet like Earth is a very exciting one to me and many others. However there are many factors that go into just making a planet suitable for life, factors such as location, temperature, water, atmosphere, and many others. Today I’m looking at some factors that play role in finding habitable exoplanets, or Earth 2.0 candidates as I like to call them. The main one I’m talking about today is the habitable zone. The habitable zone is the area around a star that a planet can have liquid water. The habitable zone is different for every solar system and is dependent on the parent star. Too close to the parent star and expect to have your oceans be boiled off. Too far and your planet would a giant ball of ice. The data I’m using for this little project comes from a site called the Habitable Zone. The site’s main purpose is to catalog planets in habitable zones and planetary equilibrium temperatures as well as many other various traits of planets.

MaddieP2F1

 

 

These are the boundaries for the habitable zone for our own solar system. The two estimated ranges for habitable zone models in our solar system are the Conservative model from 0.95-1.4AU and the  Optimistic model from .85-1.7AU (Note an AU is the average Earth-Sun distance).

 

 

 

What I wanted to compare was how the location of an exoplanet can affect the planet’s average temperature. To get my data for locations of exoplanets I looked at the optimistic model for the habitable zone. The optimistic habitable zone extends the inner/outer boundaries of a solar system by using the “Recent Venus”(closer to parent star) and “Early Mars”(farther from parent star) criteria. The more optimistic estimate refers to assuming the planet has the right atmosphere to help keep in cooler than it should be at the inner edge, and warmer than it should be at the outer edge. The picture above shows our own solar system’s habitable zone with the optimistic habitable zone being in dark green. For temperature I looked at periastron equilibrium temperatures or Teqb in the database I used. The periastron temperature is the average temperature of a planet when it is at it’s closest point to it’s parent star . It’s also important that a planet is well mixed. What that means that it has an atmosphere that can trap heat well enough and have the heat spread evenly across the planet’s surface. For context, our home planet Earth spends 100% of its time in the habitable zone, and is well mixed, with an average temperature of 290K.

MaddieP2Fr

Using the data from the Habitable Zone I made a graph comparing percentage of time spent in the THZO (the optimistic habitable zone,on the x axis) and the Teqb (average periastron temperatures in kelvins on the y axis). And for reference the blue dot represents where our own home planet Earth would sit on this plot. The results I found is that the more time a planet spent in the optimistic habitable zone (THZO) the more temperatures tended to be below at 500 kelvin, they also tend to fall into the 200-300 kelvin range which is habitable (300 kelvins being a nice warm 80.33 degrees Fahrenheit). This is especially true for those planets who spent 100% of their time the Optimistic habitable zone. Though I noticed three big outliers on the graph. One  is a planet at 1457.4 kelvin (HD 20782 b) and the other at 1547.9 kelvin (HD 80606 b). Both these measurements are above 1400 kelvins or 2060.33 degrees Fahrenheit! However these two planets only spent very little time in the optimistic habitable zone as well as having some rather eccentric orbits (which I show below). The last outlier (HD 43197 b) spent more than 75% of its time in the habitable zone however temperature managed to reach 735.4 kelvins. The one thing all these planets have in common is that during their orbits they travel dangerously close to their parent star. This may contribute to the high periastron temperatures these planets.

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Caption for three pictures above: All three of the exoplanets above for part of their orbit travel dangerously close to their parent star which is most likely the cause of the high spikes in their temperatures seen on the graph above. HD 20782 b doesn’t even spend all of it’s orbit too close to parent star or in the habitable zone. HD 20782 b spends a part of it’s orbit on the outer edge of the planets habitable zone where I would expect it temperature to drop.

Sources used:

http://www.lpi.usra.edu/education/explore/our_place/hab_ref_table.pdf

http://www.exoplanets.org/

http://www.hzgallery.org/index.html

http://www.astronomy.ohio-state.edu/~pogge/Ast161/Unit7/life.html

http://adsabs.harvard.edu/abs/2012PASP..124..323K

Asteroid Zoo

By David Torrejon (a 2016 Adler-AstroJournalist)

As I came upon the Zooniverse website, I discovered Asteroid Zoo. This project aims to explain asteroids, which are small rocky bodies that orbit the Sun. This project provides a basic introduction to asteroids, such as the classification of asteroids, but more importantly, enables the search for new asteroids. In fact, astronomers are detecting more and more asteroids every year.

DavidP1fig1from http://neo.jpl.nasa.gov/news/news189.html

As can be seen from the graph, the year appears on the X-axis and the number of new Near-Earth asteroids detected is displayed on the Y-axis. The number of detected Near Earth Objects have skyrocketed every year since 2000. In 2000 there were roughly twenty however, in 2015, there was roughly 190 probably because of the advancement of technology over the years. You may ask yourself, why detect asteroids? What’s so important about discovering irregularly shaped rocks?  But I’m here to explain the importance of asteroids.

Astronomers have found asteroids quite intriguing and important because of all the information the asteroids reveal about the solar system. The deputy principal investigator for NASA’s DAWN mission, Carol Raymond, said “The materials in asteroids represent the building blocks of the planets. ” I agree with Carol because asteroids are the earliest remains of the formation of the Solar System. They are the basic leftovers debris from the Solar System. They could potentially reveal valuable information about the emergence of the Earth or other planets.

Besides revealing important information, asteroids could be corralled and mined to provide an abundant supply of raw materials. Asteroids have been known to have Platinum Group Metals, which are some of the rarest and most valuable elements. These elements are found in the center of the Earth and cannot naturally grow in the Earth’s crust. In other words, these elements will most likely not be found in the Earth. Asteroids should been mined for their resources to address one of the Earth’s main issues, which is resource scarcity. Not only would the mining provide the Earth with resources, but it would help reduce the exploitation of Earth resources. The demand for asteroid material can lead to a resource driven economic expansionism, which can lead to the development of new innovations.

Lastly, determining the location of asteroids is very crucial for our survival. There are approximately 10,000 Near-Earth Objects (NEOs). It is possible that one day, one of these 10,000 asteroids could enter the earth’s orbit and could potentially strike the Earth, killing nearly all of the species on Earth. Recently in Chelyabinsk, Russia on February 15, 2013, an asteroid roughly 17 meters in diameter and traveling at 42,000 mph detonated in midair. The explosions released energy equivalent to 500 kilotons of TNT. The explosions injured 1,500 people and damaged property. Some people experienced retinal and skin burns. This is why determining the location of asteroids is very important, to prevent the human race from suffering the same fate as the dinosaurs. Now there is no need to worry. The odds of an asteroids striking the Earth are slim. However, if an asteroid is headed our way, we need to be aware of the asteroids.

To sum it up, asteroids play an essential role in the survival of the human race. By continuing to use telescopes to look out for NEOs, this will help us avoid an asteroid collision with the Earth. Asteroids could potentially reveal more information about the formation of our Solar System. Plus, people could take advantage of the surplus amounts of asteroids to mine for raw and scarce metals.


Bibliography
“The Asteroid Hunters.” Popular Mechanics. 2015. Web. 10 Mar. 2016.
“5 Reasons to Care About Asteroids.” Space.com. Web. 10 Mar. 2016.

Detecting Distant Solar Systems




by David Zegeye

 

Lynette-Cook-star-with-dust-862x666

(http://russjamieson.com/wp-content/uploads/2014/04/Lynette-Cook-star-with-dust-862×666.jpg)

Citizen science projects are projects that the public can get involved with on various topics ranging from humanities to astronomy. Zooniverse, which is an organization that offers various citizen science projects, has launched a new project called Disk Detective. In Disk Detective, users search for disks of dusty material around stars.

When looking at a star in infrared, which is a different wavelength of light than the light humans are able to see in, scientists may be able to see a disk orbiting around them. Disks are made of gas, dust, and debris that exist as a circular shape in orbit around a star and were formed at the star’s birth. There are two forms of disks that orbit around different stars: debris disks and YSO disks. The stars that debris disks orbit around are 5 million years old or older with the disks being mainly composed of rock and ice. YSO, short for Young Stellar Object, are young stars typically found in clusters and are about less than 5 million years old. Unlike debris disks, YSO disks are instead mostly made of gas similar to what makes up gas giant planets. YSO disks can lead to the emergence of a solar system while debris disks contain remnants of material that helped form its solar system.

Stars can emit light in various wavelengths, however, the disks that orbit them absorb the light and re-emit it in mainly infrared light, which makes the stars stand out because of all the infrared radiation that their disks emit.  Identifying potential stars that have these disks was one of the goals for the Wide-field Infrared Survey Explorer telescope, also known as WISE. However, WISE has collected too much data for scientists to analyze by themselves over the course of its mission. Due to this problem, scientists decided to open this project to the public for them to further help investigate this topic, which is why Disk Detective was created. In Disk Detective, users will be looking at images of objects in multiple types of light in order to determine whether or not the candidate satisfies the requirements to be a disk. The user selects characteristics from a list that matches up with the object that they see and their responses then get compiled together for scientists to analyze and eventually conclude whether or not the candidate fits the description they’re looking for. Scientists are asking the public to identify these stars instead of using computers because computers can’t properly determine what the object they’re looking at is since they lack the ability to make proper judgements of objects by their appearance and characteristics. Human eyes, however, are very precise when it comes to categorizing objects. This is very helpful for Disk Detective because every object that has dust looks like a blob in  images from WISE, so often looking in the optical can help you determine whether or not an object is a star or a galaxy by looking at the objects features such as cross patterns or spiral arms. These screen shots from Disk Detective help explain why the users look at objects in different types of light:

star1

The object on the left is a candidate star with a disk observed in longer wavelength of infrared. The object on the right is the same candidate star observed in optical light, thus showing more defined characteristics of the star.

gal1

The object on the left is a candidate star with a disk observed in longer wavelength of infrared. The object on the right is the same candidate object but observed in optical light, thus revealing that the object is a galaxy and not a star!

The public can get involved in Disk Detective by going to diskdetective.org and searching for stars with potential solar systems. I’ll continue my adventures in Disk Detective and report back any new findings. Until then, see you!

Why not go to an exoplanet?

by Dawna Peterson

An exoplanet is not just a planet outside of our Solar System, but it’s a planet that holds new and debateable discoveries waiting to be found. Although we cannot directly view these planets, scientists infer that an exoplanet is there based on inductive reasoning such as the fact that they are able to detect shifts in the light coming from a star if there’s a planet orbiting it.

If we can conclude that these exoplanets exist, why not design a mission for astronauts to travel there? If we can infer that they are there, what’s stopping us from further exploring an exoplanet?

An exoplanet is a planet outside of our Solar System. The nearest exoplanet is approximately 4.42 light years away, 26 trillion miles from Earth, which is nearly 10,000 thousand times the distance from Pluto to the Sun. If we are able to go at the speed of light, 3.0 x 10^8, then this would only take us 4.42 years to get there. However, the current technology is only able to go 20,000 miles per hour, so it would take 142,000 years to reach the nearest exoplanet to Earth. Scientists have not yet developed an aircraft that has been able to even come close to traveling at the speed of light. 

This trip would require generations of people to live in space because of how long it will take, and we don’t have that many people that are willing to live their full lives in space. Think about the fact that living here on Earth will be nothing like living in space for your entire life. When going to space, one needs to carry light because the more weight that we put inside of the aircraft, the more energy needed to actually move the aircraft. We don’t need a lot of fuel to travel, but we do need it to actually get to the exoplanet. Because of the need to save space and energy, there can only be a limited amount of the things needed to survive. So, when things such as food, water, or fuel runs out there is no way to renew these things for the people in space. Scientists need to find a way to renew these important things and this is something that is stopping them from traveling to an exoplanet.

Technology regarding the aircraft itself and a person’s health becomes a huge problem when it comes to attempting to travel to anything outside of our solar system. Earth’s atmosphere usually protects us from the solar rays and cosmic rays. In space, astronauts no longer have that protection, so it’s important that the deeper we are into space the better protection we have to protect our technology and our astronauts. The problem that they face presently is the fact that statistically, a week in space’s cosmic ray environment will shorten an astronaut’s life by about a day. We can only guess how much shorter someone’s life will be with a generation of people needing to be in space for 142,000 years.

The cosmic rays during the trip to an exoplanet would do serious damage to most of our technology presently because of the high energies coming off of cosmic rays, especially if we would need to go to a quicker speed than ever before. Scientists do not yet know whether or not the deeper depths of space hold high energy rays or low energy rays. There is no real way to detect the energy of the rays that are in the path of traveling to an exoplanet.Therefore, it is quite difficult to know what they are actually preparing for when building an aircraft for an area not as well known. Whatever the energy of the rays are the technology still needs to be able to withstand these high amounts of cosmic rays for a distance that is almost 4.42 light years away. Our spacecrafts that we have aren’t able to withstand cosmic rays for this long amount of time and distance. There are ideas to advance this technology such as using hydrogen- rich plastics or adding an extra sheet of metal or aluminum on the aircraft.  There are ideas such that they would build the metal on an aircraft thicker but this still will make the actual craft heavier, and it wouldn’t be much of any help because metal can’t withstand high cosmic rays for a long period of time. In addition, it is believed that this would cause an increase to secondary radiation and cause an increase to the risk of radiation depending on the energy source itself. The longer scientists take to figure out a plan to advance the technology for space travel, the longer it will take for there to be a real mission to an exoplanet in the deeper depths of space, unfortunately.

When attempting to travel outside of our solar system to an exoplanet, there is so much time, money, and brainpower that needs to go into it. There are so many things that needs to be fixed before any expedition to space can happen. There are things such as the lives of people, the cosmic rays’ power in space, the fact that we can’t renew valuable resources, and the power of current technology that goes into it. Scientists still are thinking about ways to improve these things, so that maybe one day there will be successful mission to our nearest exoplanet.

Location, Location: where would we establish another colony?

By London Westley

Typically in science fiction, humanity enters space to find that it is filled with thousands of planets, all identical to Earth, waiting to be explored and colonized. However, in real life, we aren’t as spoiled for choice. Given our limited range of travel through our galaxy, and the technology of our time, what are our options? While more planets are being found all the time, there are three places right now that are major contenders for a possible colony: the Moon, Mars, or the neighboring extrasolar, or exoplanets of Kepler 62F and Alpha Centauri Bb.

To start, here is some background information of the history of these planets as options for colonization.

The Moon:

Earth’s natural satellite has always been the first thought when considering space travel. It was the finishing point for the space race between The United States and The Soviet Union in the 1960’s. It has been fantasized as the next home of humanity in popular culture, such as in the Robert Heinlein novel “The Moon is a Harsh Mistress” or the more recent film, “Moon”. Even during the George W. Bush administration, the United States government proposed a plan for an established lunar colony by the year 2020 (the plan fell apart after the 2008 economic collapse forced the government to cut spending from NASA). Despite these setbacks for the U.S, the space agencies of the countries that haven’t made it to the moon, such as China, The European Union, India and others have been planning their own missions.

  Moon (Image credit: NASA)

Mars:

If the Moon has been the first to come to mind when thinking of where to colonize, then Mars has been a close second. Although not the object of a worldwide race between rival countries like the Moon, Mars has been the subject of a decade long series of unmanned missions by the United States, most recently via the Curiosity rover, which has found evidence of frozen water.Plans have been made for a manned mission to Mars in the year 2020, with the rover missions first testing if Mars can support a manned mission.

Mars (Image credit: NASA)

Exoplanets:

Extrasolar planets, or exoplanets, are defined as “a planet that orbits a star in a solar system other than that outside of Earth”. Exoplanet systems contain the greatest chance of finding a planet that is similar to Earth in terms of atmosphere, ecosystem, or gravity. Additionally, exoplanets are being discovered at an extremely fast rate. The planet of Kepler 62F, the fifth planet of the recently discovered Kepler star system is found to have a slightly higher mass than Earth. In the relative context of planet discovery, this is a quality that draws the attention scientists. Additionally, Alpha centauri Bb has a mass similar to Earth.

Given the specificity of what humans would need to successfully live on another planet, the three factors to consider when choosing a planet to live on are its atmosphere, its gravity, and its distance from Earth.


An artists rendition of Kepler 62F (Image credit: NASA Ames/JPL-Caltech)

 

1. Atmosphere:

A crucial factor in deciding what other planet to live on is the quality of its atmosphere. Our first colony option, the Moon, has no atmosphere, which would require us to build an artificial structure to live on it. This could be both expensive and time-consuming. Mars’ atmosphere is composed of Carbon Dioxide, Nitrogen, and Argon. This would also require an artificial structure or an attempt at Terraforming, something out of the pages of science fiction. A recently discovered exoplanet, on the other hand, could have a similar atmosphere to Earth, which could both remove the factors of cost and time.

2. Distance:

A second factor in considering where to colonize, is a planet’s distance from Earth. Given that a colony on another planet would require resources and colonists from Earth, distance is important to consider. The Moon would be advantageous in that it is only 384,400 kilometers, the closest of the three options. Mars, on the other hand, would take longer, with the distance from the Sun being 54,600,000 kilometers. Both of these distances are topped by the distance it would take to reach the nearest Exoplanet, orbiting the star of Alpha Centauri B. First, given by the fact that it is in another solar system, humanity would first have to find a way to travel 4.37 light years, the time estimated it would take light to travel there. For Kelper 62F, that distance would be 1,200 light years. Previous expeditions to both the Moon and Mars, such as the Apollo missions and the Curiosity Rover mission, have taken from 3-5 days to get to the Moon to 8 months to get to Mars.

 

3. Gravity: 

Below is a graph showing the gravities of the four planets and the moon. We know so little about the surface of Alpha Centauri Bb, that its gravity is unknown to us.

Another part to consider is the force of that planet’s gravity. The Moon’s gravity has been measured at 5.328 ft./s2. Mars is measured at 12.2 ft./s2. The gravity of an exoplanet depends on the planet. Kepler 62F has a gravity approximately 1.4 times the gravity of Earth. The following graph gives an ample comparison of the four planets. An important factor to consider are the effects a different gravity can have on the human anatomy. Depending on the gravity of the planet, the human body would have to exert more or less physical energy than it would on Earth. This could potentially have negative effects on us: If certain parts of our body are not exercised on a regular basis, that part will atrophy (a state where an organ or other part of the body withers, weakens, and dies).

When deciding the next habitat of humanity, there is no perfect option. In terms of distance, all four options require a trip of thousands or millions of miles each. While the Moon and Mars can be reached in a short period of time, it would take thousands of years for humans to reach either of the exoplanets, unless a method of going faster than the speed of light existed. The Moon has no form of atmosphere, both exoplanets could potentially have suitable atmosphere, but their compositions remain unknown. Mars, on the other hand, has some making of an atmosphere, but it is toxic to humans. Lastly, the Moon and Mars both have similarly weak gravities, and the gravity of Alpha Centauri Bb is a mystery. only Kepler 62F has the most acceptable gravity for colonization. this all contributes to the fact that with every option has its pros and cons, giving the question of where humans could colonize an unclear answer.

Faint Young Sun

by Heriberto Guzman

As the Sun gets older and older Earth gets hotter and hotter because the Sun becomes more luminous. If humans were able to go back in time they will find that the Sun will get fainter resulting in a much colder Earth. Imagine Earth, a huge ice ball rotating through space, many scientists believe that is how things were.

The Faint Young Sun paradox describes the contradiction between observations of liquid water being found in the Earth’s early history and the expectation that the Sun’s output would be only 70% as intense during that era as it is today. The reduction in the amount of light radiated by the Sun resulted in a loss of heat felt on the Earth, which was not enough for life to flourish. Any liquid exposed to the Earth’s cold surface would freeze, but that could not have been the case because geological records show existence of liquid water in rocks over 4 billion years ago! This conundrum still puzzles leading scientists. The only possible solutions are if greenhouse gases on Earth were higher in the past than they are now, or if the Earth had a much thicker atmosphere. Read on for more information!

The x-axis on the graph below is the Earth’s age; beginning at 4.5 billion years ago and ending today. The y- axis on this graph (left) is the temperature on Earth, and the y-axis (right) is the solar luminosity. You can see that as you go back in the time the Sun was less bright; the red line represents this. The blue horizontal line represents the freezing point of H2O on Earth (which is 0 degrees Celsius). The brown lines predict Earth’s temperature based on its current atmosphere (top brown line) and Earth’s temperature without any atmosphere (bottom brown line). Notice how as the solar luminosity increases so do the temperature on Earth with/ without an atmosphere. As seen on the graph the brown lines are below freezing for several billion years in Earth’s early history. However, geologists concluded that the temperature on Earth was always warm enough to host life because rocks show unique signatures of water and heat exposure , the grey area shows the measured temperature using these rocks’ signatures (geologists rock at this type of work!). So the data presented (grey area) doesn’t match the predictions made by scientists (brown lines). How is this possible?

Possible solutions to this paradox are that Earth had either better greenhouses gases or a thicker atmosphere in the past, which both could have drastically increased Earth’s temperature. Greenhouse gases are gases in the atmosphere that absorb radiation within the thermal infrared range (heat). One can think of greenhouse gases like a blanket, one’s body heat (Earth’s heat from the Sun) gets trapped in the blanket (atmosphere) and does not escape. But some blankets do a better job at warming than others, right? Greenhouse gases work the same way! Both Carbon dioxide and methane are great examples. It takes more CO2 to warm the Earth than it takes methane. Using 10 cotton blankets (CO2) will be the same as using one fleece one (methane)! So Earth could have had a thicker atmosphere (10 blankets) or just one full of better greenhouse gases like methane (fleece).

If Earth had a thicker atmosphere or better greenhouse gases in the past, geologists have predicted that it could have been within the shaded range of temperatures. The Sun is growing larger and brighter today, but was once faint and young. How did liquid water possibly exist on a cold planet? Earth having a thicker atmosphere could be a possible solution, however, scientists don’t know what happened to the thick atmosphere to get the thinner atmosphere that we have today. No one will ever know what happened… unless we develop a time machine and go back in time, which could be cool.