What Makes The Solar System Interesting To Astronomers?

Tuesday, February 17, 2015

What Makes The Solar System Interesting To Astronomers?

What Makes The Solar System Interesting To Astronomers?:

Artist’s conception of the solar system, often used in the Eyes on the Solar System 3D Simulator. Credit: NASA

While most of us are stuck on planet Earth, we’re lucky enough to have a fairly transparent atmosphere. This allows us to look up at the sky and observe changes. The ancients noticed planets wandering across the sky, and occasional visitors such as comets.

Thousands of years ago, most thought the stars ruled our destiny. Today, however, we can see science at work in the planets, asteroids and comets close to home. So why take a look at the Solar System? What can it teach us?

1. The definition of a planet and a moon is fuzzy.

We all know of that famous International Astronomical Union vote in 2006 where Pluto was demoted from planethood into a newly created class called “dwarf planets.” But the definition drew controversy among some, who pointed out that no planet — dwarf or otherwise — perfectly clears the neighborhood in its orbit of asteroids, for example. Moons are considered to orbit around planets, but that doesn’t cover situations such as moons orbiting asteroids or double planets, for example. Goes to show you the Solar System requires more study to figure this out.

2. Comets and asteroids are leftovers.

No, we don’t mean leftovers to eat — we mean leftovers of what the Solar System used to look like. So while it’s easy to get distracted by the weather and craters and prospects for life on planets and moons, it’s important to remember that we must also pay attention to the smaller bodies. Comets and asteroids, for example, could have brought organics and water ice to our own planet — providing what we need for life.

Four images of Comet 67P/Churyumov–Gerasimenko taken on Nov. 30, 2014 by the orbiting Rosetta spacecraft. Credit: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

3. The planets are all on the same “plane” and orbit in the same direction.

When considering the IAU’s definition of planets, we come up with eight: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. You’ll notice that these bodies tend to follow the same path in the sky (called the ecliptic) and that they orbit the Sun in the same direction. That supports the leading theory for the Solar System’s formation, which is that the planets and moons and Sun formed from a large gas and dust cloud that condensed and spun.

4. We’re nowhere near the center of the galaxy.

We can measure vast distances across the universe by looking at things such as “standard candles” — a type of exploding stars that tend to have the same luminosity, which makes it easier to predict how far away they are from us. At any rate, looking at our neighborhood, we’ve been able to figure out we’re nowhere near the Milky Way galaxy’s center. We’re about 165 quadrillion miles away from the center supermassive black hole, NASA says, which is probably a good thing.

A still photo from an animated flythrough of the universe using SDSS data. This image shows our Milky Way Galaxy. The galaxy shape is an artist’s conception, and each of the small white dots is one of the hundreds of thousands of stars as seen by the SDSS. Image credit:
Dana Berry / SkyWorks Digital, Inc. and Jonathan Bird (Vanderbilt University)

5. But the Solar System is bigger than you think.

Beyond the orbit of Neptune (the furthermost planet), it takes a long time to leave the Solar System. In 2012, some 35 years after leaving Earth on a one-way trip to the outer solar Solar System, Voyager 1 passed through the area where the Sun’s magnetic and gas environment gives way to that of the stars, meaning that it is interstellar space. That was an astounding 11 billion miles (17 billion kilometers) away from Earth, or roughly 118 equivalent Earth-sun distances (astronomical units).

6. The Sun is hugely massive.

Just how massive? 99.86% of the Solar System’s mass is in our local star, which goes to show you where the real heavyweight is. The Sun is made up of hydrogen and helium, which shows you that these gases are far more abundant in our neighborhood (and the Universe generally) than the rocks and metals we are more familiar with here on Earth.

Solar prominences and filaments on the Sun on September 18, 2014, as seen with a hydrogen alpha filter. Credit and copyright: John Chumack/Galactic Images.

7. We haven’t finished searching for life here.

So we know for sure that life exists on Earth, but that doesn’t rule out a whole bunch of other places. Mars had water flowing on it in the ancient past, and has frozen water at its poles — making astrobiologists think it might be a good candidate. There also are a range of icy moons that could have oceans with life below the surfaces, such as Europa (at Jupiter) and Enceladus (at Saturn). There’s also the interesting world of Titan, which has “prebiotic chemistry” — chemistry that was a precursor to life — on its surface.

8. We can use the Solar System to better understand exoplanets.

Exoplanets are so far away, and so small in our telescopes, that it’s difficult to see very much detail in their atmospheres. But by looking at the chemistry of Jupiter, for example, we can make some predictions about gas giants further afield. If we look at Earth and Neptune, we can get a better sense of the range of planetary sizes on which life could exist (those “super-Earths” and “mini-Neptunes” you sometimes hear mentioned.) And even looking at where water freezes in our own Solar System can help us better understand the ice line in other locations.

We have written articles about the solar system for Universe Today. Here are facts about the planets in the Solar System. We have recorded a whole series of podcasts about the Solar System at Astronomy Cast. Check them out here.

About Elizabeth Howell

Elizabeth Howell is the senior writer at Universe Today. She also works for Space.com, Space Exploration Network, the NASA Lunar Science Institute, NASA Astrobiology Magazine and LiveScience, among others. Career highlights include watching three shuttle launches, and going on a two-week simulated Mars expedition in rural Utah. You can follow her on Twitter @howellspace or contact her at her website.

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The National Aeronautics and Space Administration (NASA) is the United States government agency responsible for the civilian space program as well as aeronautics and aerospace research. President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA's predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

UFO SIGHTINGS PHOTO PHOTOGRAPHY

The Oxford English Dictionary defines a UFO as "An unidentified flying object; a 'flying saucer'." The first published book to use the word was authored by Donald E. Keyhoe. The acronym "UFO" was coined by Captain Edward J. Ruppelt, who headed Project Blue Book, then the USAF's official investigation of UFOs. He wrote, "Obviously the term 'flying saucer' is misleading when applied to objects of every conceivable shape and performance. For this reason the military prefers the more general, if less colorful, name: unidentified flying objects. UFO (pronounced Yoo-foe) for short." Other phrases that were used officially and that predate the UFO acronym include "flying flapjack", "flying disc", "unexplained flying discs", "unidentifiable object", and "flying saucer". The phrase "flying saucer" had gained widespread attention after the summer of 1947. On June 24, a civilian pilot named Kenneth Arnold reported seeing nine objects flying in formation near Mount Rainier. Arnold timed the sighting and estimated the speed of discs to be over 1,200 mph (1,931 km/h). At the time, he described the objects' shape as being somewhat disc-like or saucer-like, leading to newspaper accounts of "flying saucers" and "flying discs". In popular usage the term UFO came to be used to refer to claims of alien spacecraft. and because of the public and media ridicule associated with the topic, some investigators prefer to use such terms as unidentified aerial phenomenon (or UAP) or anomalous phenomena, as in the title of the National Aviation Reporting Center on Anomalous Phenomena (NARCAP).

UFO PHOTO PHOTOGRAPHY

UFO - Unidentified Flying Object An unidentified flying object, or UFO, in its most general definition, is any apparent anomaly in the sky that is not identifiable as a known object or phenomenon. Culturally, UFOs are associated with claims of visitation by extraterrestrial life or government-related conspiracy theories, and have become popular subjects in fiction. While UFOs are often later identified, sometimes identification may not be possible owing to the usually low quality of evidence related to UFO sightings (generally anecdotal evidence and eyewitness accounts). Stories of fantastical celestial apparitions have been told since antiquity, but the term "UFO" (or "UFOB") was officially created in 1953 by the United States Air Force (USAF) to serve as a catch-all for all such reports. In its initial definition, the USAF stated that a "UFOB" was "any airborne object which by performance, aerodynamic characteristics, or unusual features, does not conform to any presently known aircraft or missile type, or which cannot be positively identified as a familiar object." Accordingly, the term was initially restricted to that fraction of cases which remained unidentified after investigation, as the USAF was interested in potential national security reasons and/or "technical aspects" (see Air Force Regulation 200-2). During the late 1940s and through the 1950s, UFOs were often referred to popularly as "flying saucers" or "flying discs". The term UFO became more widespread during the 1950s, at first in technical literature, but later in popular use. UFOs garnered considerable interest during the Cold War, an era associated with a heightened concern for national security. Various studies have concluded that the phenomenon does not represent a threat to national security nor does it contain anything worthy of scientific pursuit (e.g., 1951 Flying Saucer Working Party, 1953 CIA Robertson Panel, USAF Project Blue Book, Condon Committee).

Photos of Nature | Nature Photography What is The Universe

Photos of Nature | Nature Photography What is The Universe

Tuesday, February 17, 2015