The Universe Beyond Our Solar System: A Fascinating Place
Mysteries of the Universe
The universe is a mysterious and fascinating place. Astronomers have long believed that about seventy percent of its total mass and energy exists as dark energy, which is believed to be responsible for the universe’s accelerating expansion. Another twenty-five percent is thought to be made of invisible dark matter. This type of matter does have mass but doesn’t reflect light and can’t be seen. Less than five percent of the universe is believed to consist of the “regular” matter that we can see.
Very little is known about dark energy and dark matter, despite the fact that they are believed to be so common in the universe. They are strange and intriguing concepts. An understanding of their nature would be a huge advance in our knowledge.
Scientists have other puzzling ideas about space. For example, the evidence indicates that the universe is expanding, but some researchers say that it may also be infinite. How do these two ideas fit together? Another fascinating idea proposed by some researchers is that other universes exist in addition to our own, forming a multiverse. Some scientists also suggest that our universe was produced as a bud or branch from another universe and in a similar way is producing other universes. Every new theory or new discovery in astronomy is exciting.
"Dark" energy received its name because it's mysterious and theoretical. A new theory from scientists at the University of Copenhagen suggests that the concept of dark energy should be replaced by one of dark matter that exerts a magnetic force. More evidence is needed to confirm this interesting idea.
Nebulae, Stars, Galaxies, and Planets
The space between stars is not a vacuum. It contains a thin mixture of gas and dust known as the interstellar medium or ISM. The main component of the ISM is hydrogen, which exists in a molecular, atomic, or ionic form, but other substances are also present. The interstellar medium gives rise to some interesting entities.
Nebulae (or Nebulas).
Nebulae are clouds of gas and dust formed when interstellar medium partially collapses due to gravitational attraction between the particles. Nebulae contain mainly hydrogen and helium. Some glow, and some are colored. The beautiful photos of nebulae that are shown on astronomy websites may have been color enhanced in order to approximate their real appearance, however. Nebulae often produce stars.
Stars and Nuclear Fusion
A star is "born" as particles in a nebula move even further towards each other under the influence of gravity. Part of the gas and dust cloud collapses to form the star. The temperature increases during the collapse, eventually becoming high enough to trigger nuclear fusion to begin. In nuclear fusion, nuclei of atoms join, producing the star's immense energy in the process.
Galaxies and the Milky Way
A galaxy is a collection of stars, gas, and dust. Scientists know that our galaxy—the Milky Way—contains other solar systems beyond our own, each with a star surrounded by orbiting planets. NASA says that 3,200 solar systems have been discovered in the Milky Way to date and that probably many more exist. They also say that the Milky Way contains around 100 billion to 400 billion stars. Space statistics are often impressive. Many other galaxies exist beyond the one in which we live.
Planets generally orbit a star due to gravitational attraction. So-called "rogue planets" exist, however. A rogue planet travels through space instead of around a star. There is a lot that is unknown about the entities. One theory for their creation is that a collision of some kind knocked a planet out of its orbit around its star. Another is that planets can sometimes form outside of solar systems. Rogue planets have been discovered within the Milky Way and outside it.
When this article was last updated, the NASA website stated that the existence of 4,528 exoplanets (ones beyond our solar system) had been confirmed.
The Life Cycle of a Star
Scientists talk about the "lives" of stars, since stars change over time. They are born in nebulae. Their fate in old age depends on their mass.
Low Mass Stars
A star with a low mass ends its life as a red dwarf. Red dwarfs are thought to be the most abundant type of star. They exist for a long time and release their energy very slowly. Astronomers suspect that some may be able to live for trillions of years before they run out of fuel.
Medium Mass Stars
A medium mass star like our sun will become a red giant as it ages, then change into a white dwarf, and finally become a cold and dark black dwarf. The sun is believed to be about 4.5 billion years old and is middle aged at present.
High Mass Stars
A high mass star has a more violent life than a low or medium mass star. As it ages it turns into a red supergiant and then undergoes a dramatic explosion called a supernova. The material remaining after the explosion becomes a neutron star, or in the case of a very massive star, a black hole.
Gravity is the force of attraction between objects. The larger the mass of the objects or the shorter the distance between them, the stronger the force of gravity.
Neutron Stars, Magnetars, and Pulsars
A neutron star is only about 20 km in diameter, yet it has a mass of about 1.4 times the mass of the sun. Its gravitational field is so intense that protons and electrons are pulled together to form neutrons, giving the object its name. It also has a strong magnetic field. In addition, neutron stars rotate rapidly. Some spin at a speed of more than 700 rotations per second.
A magnetar (magnetic star) is a neutron star that has an extremely strong magnetic field. The field is around a thousand times greater than that of a "regular" neutron star. Based on discoveries made so far, magnetars generally rotate more slowly than other types of neutron stars. They are a rare entity, however, and there is much that is unknown about them. In 2020, NASA's Chandra X-ray Observatory discovered a magnetar that was also a pulsar.
A pulsar is a neutron star that rotates rapidly and produces a beam of electromagnetic radiation from a particular point. As we view a pulsar from Earth, the beam appears to be turning on and off at regular intervals due to the rotation of the pulsar. The beam consists of visible light, radio waves, x-rays, gamma rays, or more than one type of electromagnetic radiation.
The Electromagnetic Spectrum
The Chandra Observatory Describes Neutron Stars
A neutron star is so dense that on Earth one teaspoonful would weigh a billion tons...In a typical neutron star, the magnetic field is trillions of times that of the Earth's magnetic field; however, in a magnetar, the magnetic field is another 1000 times stronger.— NASA
A black hole isn't an empty spot in space, as its name might suggest. Instead, it's a place where matter with a very large mass is filling a very small space. Since a black hole has such a huge and concentrated mass, it exerts a tremendous force of gravity. The gravitational force is so strong that it's often said that no light can escape from the area. Some recent research has suggested that the common assertion that black holes never release light may not be true. They may be able to reflect light in certain situations.
Scientists detect black holes by their effects on the objects that surround them. An object may be torn apart as it's pulled into a black hole. The object accelerates as it gets nearer to the "hole" and emits radiation in the form of x-rays.
Most galaxies—including our own—have a supermassive black hole at their center. The one at the center of the Milky Way is believed to have a mass that is 4.5 million times greater than the sun's mass. It's located twenty-eight thousand light years away from the Earth. A light year is the distance that light travels in one year, which is 9.46 X 1012 kilometers or 5.88 X 1012 miles. The Milky Way also contains many smaller black holes.
Think of a star ten times more massive than the Sun squeezed into a sphere approximately the diameter of New York City.— NASA (Description of a black hole)
Quasars (quasi-stellar radio sources) are very distant, brilliant objects that are releasing an enormous amount of energy. To us, they look like a pinpoint of light, just like a star. This is due to their huge distance from Earth. Astronomers say that quasars are actually releasing far more energy than a star.
Scientists think that a quasar is located in the center of a distant galaxy and is in some way obtaining energy from a supermassive black hole. The quasars that we see today may no longer exist, however. The light emitted from a distant object in space takes a very long time to reach Earth. When we examine distant space, we are seeing it as it once existed, not as it exists today.
Researchers suspect that quasars are only present in the early stage of the formation of a galaxy. There may once have been a quasar in our own Milky Way galaxy.
There is much that is not yet understood about the universe. Intriguing areas of study include the origin and possible fate of the universe, fields and the disturbances within them, gravitational waves, exotic and unusual particles, and the behavior of objects in space.
Many puzzles about the universe exist. Some of them are tantaIizing. I love to lie comfortably on the ground on a clear night, look up at the stars and planets that can be seen, and think about the universe. Speculation is fun. Knowledge would be even better.
It’s frustrating to realize that there is so much that is unknown about space and to think about how difficult it is to study the universe from our little area within it. New techniques for exploring space are being created, however, which provides some hope. It’s awesome to explore the night sky and to think about all the possibilities.
Despite the facts that are being discovered, the universe beyond the solar system still contains mysteries. I contemplate some of them in my poem below.
Mysteries of the Universe
I want to see the universe beyond the Earth,
to reach beyond the confines of this world
and travel far beyond the sky
to new and ancient mysteries
outside this comfort zone,
smaller than a tiny speck
lodged in the universe’s eye.
I'd love to see the stars beyond the night
and experience the awe,
to view the wondrous scenes
of destruction and of birth,
the cosmic acts of power
and fire of novelty
in nature never still.
I’d like to walk upon another world
and fly through space above,
senses nourished and enthralled.
I want to marvel at strange life,
to know dark matter and dark energy,
to see creation in the act
and explore the vast unknown.
I’d love to find out why? what?...and even who?
and then move on to find the end of space and time
if such a place or thought exists;
or make the giant leap
beyond the universe,
a never ending trail
into the infinite beyond.
- Information about dark matter and dark energy from CERN (the European Center for Nuclear Research, which is based in Switzerland)
- New study casts doubt on the existence of dark energy from the ScienceDaily news service
- Discovery of a new rogue planet from CNN
- Life cycles of stars from NASA
- Facts about pulsars from the space.com website
- Information about black holes from NASA
- First light detected from behind a black hole from Cosmos Magazine
- Quasar facts from earthsky.org
The NASA website contains many other facts and statistics about space in addition to the topics mentioned above.
© 2011 Linda Crampton