While growing up, do you remember looking up into the sky during the day and saying, “What is that bright thing making my eyes hurt?”or at night, saying,“What is that big circle in the sky with light coming off of it?”Well, I was the kid whowould want the answers to those questions; I thought it was interesting. I was always entertained by the statement the sun rises in the east and sets in the west. The sun and moon have always been an interest of mine, hence why I decided to take astronomy! One question I have had for a while now and have wanted to research for myself is how did the sun and moon form? I discoveredmany different beliefsonhow the Sun and Moonwereformed, and in this paper, my objective is to display these theories.
There are many so called sources out there but only some are credible. I referred to the website skyandtelescope.com very often as they are credible. It is believed today that the sun came into existence about 4.6 billion years ago. Many scientists agreethat the sun and the rest of the solar system formed from a giant, rotating cloud of gas and dust or the solar nebula. According to space.com, the nebula collapsed thanks to gravity making it spin faster andit later flattened into a disk. Most of the material was pulled toward the center forming the sun.
There are other possibilities of how the solar system, including the sun, formed.According to skyandtelescope.com, a new theory suggests that the solar system formed within the shell of a wind-blown bubble surrounding a dead star. “From one star’sashes, another is born” (Hall). Most of the elements in the periodic table are orchestrated within thenuclear furnaces,or stars,in the night sky. When the stars reach their end, they send that material away. This will “seed the cosmos with heavier elements that get swept up within the gas that will soon form new stars” (Hall).
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It then goes on to state how the sun is no exception and that the solar system formed from all the leftovers of past stars. A new study, which was published in The Astrophysical Journal Letters,states that the Sun came together at the edge of a wind-blown bubble surrounding a dead star which suggests that the solar system formed in an atypical or unusual environment. Meteorites give us clues about how the solar system actually formed. One example comes from themid 1970’s, scientists discovered that one meteorite contained stable daughter isotopes of aluminum-26, which then made them believe that the early solar system was basically overflowing with the aluminum radioisotope which was short-lived.
For this radioisotope to have been a part of the early solar system, scientists hypothesized that it must have been caused by a so called “cataclysm” or a stellar explosion. With the help of this thought, scientists developed the ideathat a supernova ejected material into a dense cloud of interstellar gas and dust, causing it to collapse to form our sun. Recently, itwas discovered that there was too little iron-60 in several meteorites. “It was an odd discovery given that a nearby supernova would have produced iron-60 along with aluminum-26” (Hall). Now, scientists had to determine the reason why a supernova would eject one isotope but not the other. One possibility wasthegiant Wolf-Rayet stars which weigh in at 25 times the mass of the sun.
Wolf-Rayet Stars can remove elements from their surfaces with intense solar winds. The winds contain plenty of aluminum-26 butvery small amounts of iron-60. The sun could have formed within the walls of this “vast cosmic bubble.” Particularly, the star would eject the aluminum-26 which are carried on grains of dust.The grains have enough power and momentum that they could punchthrough one side of the wall, which would deposit the aluminum. Then, once the Wolf-Rayet Star dies, the bubbles wall cools and parts of it collapse to form new stars which includes our sun.
Another scientist argues that the sun likely formed within a star-forming region that was basically polluted with Wolf-Rayet stars, but not so much polluted with supernovae explosions. The reason is because supernovae form from stars that are smaller than Wolf-Rayets. Therefore, these stars have longer lifetimes and more time to travel far away from the star forming region, while the Wolf-Rayet staysput and hasless time to move. Overall, Iron-60 will be evenly distributed throughout the galaxy while aluminum-26 will mainly be found in the star-forming regions. The scientist believes this is more likely because the amount of aluminum-26 found in meteorites matches the amount in star forming regions. He also argues that “it’s unlikely the Sun formed in an environment as special as the edge of a dead star’s wind-blow bubble” (Young).
These are some of the possible ways that the sun came about. The sun has enough fuel to stay how it is for another 5 billion years, but after that it will become a Red Giant and later it will shed its outer layers to become a white dwarf. In my opinion, after researching the possibilities of how the sun formed, I was very intriguedby the idea that the Sun came together at the edge of a wind-blown bubble surrounding adead star. Thissuggests that the solar system formed in an atypical or unusual environment. This is a relatively new idea that wascaused by a stellar explosion.
Just picturing this idea makes it very interesting for me. Space.com was a great source to use because it narrowed down the different theories of the Sun’s origin, whileskyandtelescope.com offered several different views. My understanding of the topic has changed becauseI learned that there is not only one possible way that the Sun formed, but there are actually many different possibilities, with some still being tested today. I feel that it is definitelyimportant to not always believe the first thing you see and to always look further. I learned a lot while researching this topic, asI had always believed that the sun just formed 4.6 billion years ago. I have never heard about things such as a Wolf-Rayet Star, which can remove elements from their surfaces by an intense solar wind, or how meteorites can actually give us clues to how the solar system formed.
Besides trying to understand how the sun was formed, I amalso interested in how the moon was formed. The prevailing theory today is the Giant Impact Hypothesis which states how an object smashed into young Earth forming the moon. But this is not definite, as the subject is still being studied today. According to skyandtelescope.com, “New studies offer contrasting scenarios for making the moon. One argues for a one big splat early in solar-system history; a second envisions a score of lesser blows that built up the Moon over time; and a third suggests water was involved”(Beatty).
Again, we are given several different possibilities that are still being researched today!It is amazing that with all the information we have today, we still do nothave an answer on how the Moon formed.The problem is that three decades ago, scientists showed that a body about the mass of Mars could have struck Earth and ejected enough debris into orbit to collect into a Moon-sizedobject. The simulations show that what ends up in the Moon came from the impactor, not Earth. Although, the Apollo and Luna samples show how the Moon and Earth have a very similar composition. Lunar meteorites area great example of this. Moon rocks match Earth’s isotopic ratios for the elementstitanium, calcium, silicon, oxygen and tungsten.
But, only 1% or 2% of the time do the simulations show a Moon with an Earthlike composition. “There’s also a problem of fine-tuning the impact to yield the angular momentum of the current Earth-Moon system”(Beatty). To further the topic of the possibility of the moon coming from Earth, I discovered another article on skyandtelescope.com. This article states that new findings show the Earth and Moon have identical isotopic ratios of tungsten. Before the space age, many astronomers believed in three possibilities: The Moon formed with Earth, the Moon wascaptured into orbit when it passed close by, or it literally tore away from a hyper-spinning Earth. Today, scientists are mostcomfortable with the belief that the Moon came about after an object the size of Mars (Theia) struck the infant Earth with a so called “titanic glancing” blow. Some of the ejected debris formed a single large satellite.
The concept was proposed by WilliamHartmann and Donald Davis in 1975 and has gained popularity over the years thanks to detailed computer modeling by Robin Canup. Canup’s models showthatthe Moon would have formed largely from the impactors mantle, rather than Earth’s mantle. Thus, Theia’s iron-rich core was swallowed up by Earth. The ratios of oxygens three isotopes are the same in lunar and terrestrial rocks. It is thought that Theia was in an orbit much like Earth’s before it struck. Or that oxygen isotopes mingled and mixed freely between Earth and the ejected matter in the collisions white-hot aftermath.A cosmochemist from the University of Chicago showed how the ratio of two titanium isotopes are likely a dead match in samples from the Moon and Earth.
The chemist also notes how the Moon and Earth have the same isotopic ratios of tungsten. For the tungsten ratios to match, along with titanium and oxygen, the interior of Theia and the young Earth would have had to evolve the same way. She notes how it is very unlikely but not impossiblethat this occurred. According to researchers Raluca Rufu, Oded Aharonson, and Hagai Perets from Israel, the notion of one giant impact is wrong. Theythink that Earth had dozens of smaller impactswith objects between 1-10% of its mass. Each impact ejected debris into an orbiting disk. The rings quickly thickened into moonlets and tidal interactions with the “young” Earth then drove each of them outward. This process could take up to 100 million years!
Over time, they formed the Moon. This approach produces a lunar composition that’s a mix of manyothercompositions. The most Earth-like contributions came from the nearly head-on collisions that drilled deeply into our planets mantle. It is possible though that a couple of later impacts could have tweaked the systems angular momentum to match what we now have. One scientist notes, “Lower energy moonlet forming impacts would leave parts of Earth unscathed. Distinct, terrestrial geochemical reservoirs may therefore have survived Moon formation” (Collins).
Researchers have discovered and identified portions of Earth’s mantle that do not match in composition with the rest of our planet.Another issue besides how the Moon actually formed is how long after the solarsystem came tobe did the moon form? Some planetary scientists have argued that the Moon might have formed 150 to 200 million years after the solar system began. Others say it showed up much sooner, within a few tens of millions of years. One new analysis published thisyear in “Science Advances”maintainsthat the Moon came together very quickly and had mostly solidified by 4.51 billion years ago, meaning 60 million years after the solar systems birth.
The evidence was found in 8 small grains of the mineral zirconor ZrSiO4. This was collected by Apollo 14’s astronauts who found traces of uranium, lead and hafnium. A couple of years ago, a different research group analyzed these same grains and also came up with an early formation age. The results were uncertain because of the technologies used. The group of scientists redid the age-dating, carefully measuring the lead-isotopes,which resulted from the radioactive decay of uranium-235 and -238. They also determined the decay oflutetium to hafnium and corrected the lunarsexposure to cosmic rays. They feel the age of 4.51 billion years has an uncertainty of no more than 10 million years and that the Moon might actually be older.
The Apollo 14 zircon grains crystallized from the deep lunar magma ocean that existed right after the Moon came together. “This would have happened if the Moon assembled as white-hot debris after a single, catastrophic impact with Earth –but it isless likely if dozens of little cooled off moonlets coagulated into a single whole” (Beatty).
