A Greedy, Gluttonous Galaxy

It’s no secret that the universe is growing. However, research leads us to believe that our own Milky Way Galaxy is growing as well. In fact, our galaxy exhibits cannibalistic behavior, absorbing material from the dwarf galaxies surrounding it. We know that the chemical makeup in the central bulge of our galaxy differs from the chemical makeup of the outer halo of our galaxy, and we have also found that the chemical makeup of the outer halo of our galaxy is similar to the chemical makeup of stars found in dwarf galaxies orbiting our galaxy – namely, the Large Magellanic Cloud and the Sagittarius Dwarf Elliptical Galaxy. Therefore, these dwarf galaxies may simply be the leftovers of galaxies that were long ago absorbed into our own galaxy.


Milky Way Galaxy

Astronomers believe the key to understanding the growth of our galaxy is learning more about the dark matter around our galaxy. The halo of dark matter surrounding our galaxy actually exerts a gravitational force on smaller, neighboring galaxies, so it may be that dark matter is ripping away stars and pulling them into the external regions of our galaxy. There are still so many unanswered questions about dark matter and dark energy, but a project called the Dark Energy Survey is currently underway, in which we are using a tool called the Dark Energy Camera to detect stellar streams. Stellar streams are groups of relatively few stars that have been ripped away. They are difficult to detect because we are looking for a small number of stars in such a large region of space. Nevertheless, these stellar streams illustrate how our galaxy is constructed from smaller galaxies, so the future findings of the Dark Energy Survey should prove exciting!






European-Extremely Large Telescope

The European Southern Observatory began construction of the European-Extremely Large Telescope (E-ELT) back in 2014. This telescope is on track to be the world’s largest optical and infrared telescope by the time it is completed in 2024, thus living up to its name. The E-ELT will include a main mirror that is 128 feet in diameter, beating out some of its competitors, such as the Giant Magellan Telescope and the Thirty Meter Telescope, which boast main mirrors that are 82 feet and 98 feet in diameter respectively. This telescope will be able to capture images 16 times sharper than images captured by the Hubble Space Telescope.

The E-ELT will be used to study exoplanets, dark matter, supermassive black holes, galaxy formation in the early universe, and much more. Observations from this telescope may be able to answer questions such as if the laws of nature really are universal, and we may be able to learn more about stellar populations at distances of tens of millions of light-years away from us. The E-ELT will be operating in northern Chile’s Atacama Desert, an ideal location for astronomical observation due to the dryness of the air and the clarity of the night sky. However, Chile, like most other locations in the world, still suffers from light pollution, so efforts to limit blue light emissions and luminous signs have come about.

Astronomers hope the E-ELT will be in use for at least 30 years. At a price of $1.4 billion, I would sure hope so. The more technology advances, the more we will be able to learn about our universe. The farther distances we will be able to look out to, and the more we will be able to essentially look back in time. I’m excited for the astronomical discoveries bound to emerge. However, given the fact that we have just over six and a half years left until the E-ELT’s first light, we’ll just have to be patient for now!







Historical Astronomers in Context

Galileo Galilei made many important contributions to astronomy during his lifetime. He created his own increasingly powerful telescopes. He discovered that the Moon’s surface wasn’t smooth, as it had been previously thought. He observed four moons revolving around Jupiter. He discovered many more stars with his telescopic observations. He found that Venus has phases just like the Moon. He determined that the Sun has sunspots. Galileo’s observations were extremely significant evidence in favor of the Copernican theory, undermining the geocentric model of the universe, and he held the idea that the Earth revolves around the Sun long before it became accepted among the scientific community.

Galileo Info

            During Galileo’s lifetime, on July 25, 1593, King Henry IV of France converted from Protestantism to Roman Catholicism. This was important because King Henry IV was viewed extremely unfavorably by Protestants afterward, and he would eventually declare Catholicism as the state religion. A little later in Galileo’s lifetime, on December 21, 1620, the Pilgrims on the Mayflower arrived in America, founding the Plymouth colony in Massachusetts. There they began building their town, with the community government to operate under the signed agreement known as the Mayflower Compact. William Shakespeare was born on April 26, 1564 and died on April 23, 1616, meaning that William Shakespeare lived at the same time as Galileo for Shakespeare’s entire life. Shakespeare was a critical figure in literature because he garnered success and acclaim for the plays he wrote, and his plays are still studied and performed to this day – over four centuries later.

16th/17th Century Events

King Henry IV

The Pilgrims

Shakespeare Biography

            It was interesting to learn about the importance of King Henry IV converting to Roman Catholicism because it reminded me how intertwined politics and religion were back then. Additionally, it reminded me that Galileo’s observations must have been especially unpopular due to their conflicts with the beliefs within the church. While Galileo was making scientific contributions in Italy, America was just getting started, with the Pilgrims getting settled in Plymouth. This made me think about how relatively quickly America emerged as a world power compared to other developed countries that had existed well before America had even been discovered. It was definitely interesting to learn that one of the most important figures in scientific history existed at the same time as one of the most important figures in literary history, and finding out that both only became as popular of figures as they are long after their deaths made me realize how common of a theme this is for geniuses throughout history.

Putting the speed of light into perspective

The theory of special relativity tells us that there is an absolute speed limit in the universe, that being the speed of light. At a speed of about 300,000 km/s, light takes only one second to travel to the Moon from Earth and eight minutes to travel to the Sun from Earth. This speed is extremely fast for human standards. For instance, in 2016, NASA’s Juno spacecraft arrived at Jupiter, accelerating to a speed of about 265,000 km/h. This made it the fastest human-made object in history. Still, this speed of 265,000 km/h is nowhere close to light’s speed of 300,000 km/s.

However, not even light seems fast in the context of just how massive our universe is. For example, it takes light four years to reach Earth from Alpha Centauri, the star system nearest to us besides the Sun. It takes light 6,000 years to reach us from the Crab Nebula, the remnant of a massive star in the direction of Taurus. It takes light 2 million years to reach us from the Andromeda Galaxy, the nearest galaxy to our own. It takes light 650 million years to reach us from the Hercules Cluster of galaxies. Keep in mind, the universe’s expansion started approximately 14 billion years ago, so there are even farther objects that light would take even longer to travel to Earth from!

Given these facts, convenient interstellar space travel seems like an impossible feat. The fastest object humankind has managed to create couldn’t even travel in an hour the distance that light travels in a second. And our spacecrafts that humans can actually travel on are even slower! So if we can’t travel faster than light, and light takes at least millions of years to reach nearby galaxies, then traveling through the universe like we’re in Star Trek seems hopeless!

Nevertheless, it is important to point out that special relativity involves local laws of physics. We may not be launching rockets faster than the speed of light, but general relativity tells us that these rules do not apply for galaxies at the far side of the universe. So does that mean a speed faster than the speed of light exists in the universe? In fact, the universe expands faster than the speed of light. The observable universe is only some fraction of the entire universe. Additionally, we know that the early universe underwent a phase of rapid, exponential expansion, and more distant objects move faster away from us than less distant objects.

Therefore, it makes sense that there would have been points during the entire universe’s expansion in which objects were moving away from other objects faster than the speed of light relative to each other or that the very distant objects at the outermost parts of the universe that are moving away faster and faster away from us will eventually exceed the speed of light if they have not already. As for the question of whether or not humans will find a way to exceed the speed of light, we may have to simply hope that we will someday find a way to use wormholes to transport to other worlds!


Universe Expansion (from Scienceline)