Understanding the universe
Gazing up at the night sky, you may wonder about the stars twinkling above you.
How far away are these tiny glimmers of light? what lies beyond the stars?Where does our tiny planet fit in?
Join us on an exploration to answer some of these mysteries. We'll find out how vast the Universe is, how and when it all began, meet scientists who helped us understand space, and visit a few galaxies beyond our Milky Way.
A star -studded turn around the Milky Way and Beyond.
Are you ready for the ultimate field trip? We'll start in our own cosmic neighborhood, the Milky Way, then zoom out to other galaxies of the universe. You're about to discover that one size(or shape) fits all definitely doesn't apply to these huge collections of stars, gas, and dust.
Thing to know before you go.
Galaxies are enormous swarms of stars, dust, gas and dark matter held together by gravity. The sun is one of about 100 billion stars in our own galaxy, called the Milky Way. If you think that's incredible, imagine this: The Milky Way is just one of billions in the observable universe!
Most galaxies are found in clusters of about 150 galaxies, bound together by each other's gravity. Our Milky Way is part of a small cluster of some 30 galaxies called the Local Group. Clusters of galaxies are often collected in superclusters. Our Local Group is part of the Virgo Supercluster, which contains several thousand galaxies.
Galaxies Range in size, containing anywhere from 100,000 to 3 trillion stars! They also come in different shapes. There are three major types of galaxies:
Spiral galaxies are shaped like disks and look like pinwheels from above. Young stars are found in the arms, and older are found in the central bulge, or nucleus.
Elliptical galaxies are the oldest and largest galaxies. They are smooth and oval and contain many old stars. There are many more elliptical galaxies in the universe than spiral galaxies.
Irregular galaxies don't have a distinct shape and are not symmetrical like spiral or elliptical galaxies. They may be young galaxies that have not yet formed a symmetrical shape, or their irregular shape may be caused by two galaxies colliding.
It's awesome. Grasping light
years and other cool but mind-boggling concepts.
Light Years/Measuring Unimaginable Distances
The distance between stars and galaxies in the universe
is so vast it would be unwieldy to describe it in miles-like measuring
the distance from New York to Tokyo in inches! Instead, scientists
use light-years to measure distances in space. This sounds like
a unit of time, but a light-year is actually a distance; the distance
that light travels in one year.
Did you know that when you gaze up at objects in the night sky, you're looking back in time? How far back you see depends on how long it's taken light from that object to reach you? The farther this object, the farther back in time you see.
Light from the moon-which is very, very close in space-takes about 1.3 seconds to travel to Earth. So you see the moon as it looked just over a second ago.
The sun is much further; its rays take about eight minutes to reach Earth.
Saturn is an average of 10
times farther from the sun than Earth. We see Saturn
Once you look beyond our solar system, objects are so far away it takes more than hours or even days for light to reach us. We're seeing objects as they looked years ago. Click the images belows to look through the telescope at objects in space-and find out how far back in time we're looking.
The history of the Universe
It's hard to grasp the size of the universe, it's equally hard to imagine its age. Astronomers calculate that the universe originated about 13 billion years ago in an explosion of space called the big bang. At that time, all the matter and energy in our observable universe was packed together in a volume smaller than an atom.
No one knows what happened before the big bang or what caused the explosion-our laws of physics can't explain it-but in an instant the energy and matter of our universe poured into existence and expanded with space itself. We still see the evidence of the big bang today, as the superclusters of galaxies continue to fly apart from each other. We also observe the remnant glow of the big bang itself in the form of faint microwave light from all parts of the sky.
Timeline of the Universe
The early universe was small and intensely hot. As the universe expanded and cooled, small particles condensed and formed the elements hydrogen and helium. Over billions of years gravity allowed the cooling gases to collapse into galaxies, stars, and planets, including the Earth. Here's a timeline of important events in the history of the Universe. The timeline is in billions of years, so we need a magnifying glass to show when events occurred only millions years ago.
For a truly unique perspective on the history of the Universe, check out the "Universe in One Year." This shows the past 13 billion years compressed into a single year!
The Universe in One Year
Imagine that the history of the universe is compressed into one year-with the big bang occurring in the first seconds of New Year's Day, and all our known history occurring in the final seconds before midnight on December 31. Using this scale of time, each month would equal a little over a billion years. Here's a closer look at when important events would occur when we imagine the universe in one year.
Jan: New Year's day. The Big Bang
March: Milky forms.
August: Sun and planets form.
September: Oldest known life forms:(single celled)
November: First multi cellular organism appeared.
Although space can be a popular and exciting topic for your students, describing the Universe presents quite a challenge. Its history, size, and elements may be difficult to grasp since they often can't compare to anything we understand on Earth. "Understanding the Universe" introduces your students to important concepts of the Universe:where the Earth fits into the larger picture of the Universe, how vast and far away places are in the Universe, and prevailing theory about when and how it all began. Students will also learn about important scientists and astronomers that have contributed to our knowledge of the Universe. And finally, they will explore galaxies, the "building blocks" of the Universe-from our own Milky Way to other galaxies both nearby and near the other side of the Universe.
This area is designed to introduce students to the incredible size and history of the Universe. Galaxies are important components within the Universe. This tour introduces to students to galaxies-from their basic makeup to their different shapes. This journey begins in the Milky Way, then takes them to neighboring galaxies, unusual galaxies, and the farthest galaxies ever known. along the way,
Finding the Earth in the Universe
Ask students how they would explain their address to someone who lived in another country. They might say their street address, city, state, and country. Now ask them to think about how they would describe the Earth's location to someone in another galaxy. Explain that the Earth is just one planet that revolves around the sun in the Solar system. The sun is just one of billions of stars within the Milky Way Galaxy. The Milky Way is one of 30 galaxies in a cluster of galaxies called the Local Group. and the local group is just one cluster within a "supercluster" called the Virgo Supercluster. The Virgo Cluster is a tiny part of the entire Universe. Have students use this information to write their "space address".
How it all began: A short History of the Universe
Review the Timeline of the Universe, which begins with the Big Bang occurring 13 billion years ago, to learn when our galaxy, sun, and Earth formed. The Universe in One Year looks at these events and the evolution of life on Earth in a new way. Before you show students this section, ask them to imagine the Universe as compressed in one single year-with the current time the moment of the clock strikes midnight on New Year's Eve. Ask them to predict when certain events would have occurred if the Big Bang happened on New Year's Day. In what month do they think the Sun would form? In what month would the first plant appear? How many month or day would the dinosaurs roam the Earth? After viewing the calendar, ask students what events and dates surprised them most. Challenge them to estimate what the "Earth in One Year" might look like, with the formation of on January 1st.