Poster’s Note: One of the many under-appreciated aspects of NASA is the extent to which it publishes quality science content for children and Ph.D.’s alike. NASA Space Place has been providing general audience articles for quite some time that are freely available for download and republishing.
The following three short articles are reproduced in part below with links to the complete articles.
Space Place – What Is an Earthquake?
An earthquake is an intense shaking of Earth’s surface. The shaking is caused by movements in Earth’s outermost layer.
Why Do Earthquakes Happen?
Although the Earth looks like a pretty solid place from the surface, it’s actually extremely active just below the surface. The Earth is made of four basic layers: a solid crust, a hot, nearly solid mantle, a liquid outer core and a solid inner core.
Caption: A diagram of Earth’s layers. Earthquakes are caused by shifts in the outer layers of Earth—a region called the lithosphere.
The solid crust and top, stiff layer of the mantle make up a region called the lithosphere. The lithosphere isn’t a continuous piece that wraps around the whole Earth like an eggshell. It’s actually made up of giant puzzle pieces called tectonic plates. Tectonic plates are constantly shifting as they drift around on the viscous, or slowly flowing, mantle layer below.
Read the rest at: spaceplace.nasa.gov/earthquakes/en/
Space Place – What Is a Light-Year?
Caption: An image of distant galaxies captured by the NASA/ESA Hubble Space Telescope. Credit: ESA/Hubble & NASA, RELICS; Acknowledgment: D. Coe et al.
For most space objects, we use light-years to describe their distance. A light-year is the distance light travels in one Earth year. One light-year is about 6 trillion miles (9 trillion km). That is a 6 with 12 zeros behind it!
Looking Back in Time
When we use powerful telescopes to look at distant objects in space, we are actually looking back in time. How can this be?
Light travels at a speed of 186,000 miles (or 300,000 km) per second. This seems really fast, but objects in space are so far away that it takes a lot of time for their light to reach us. The farther an object is, the farther in the past we see it.
Our Sun is the closest star to us. It is about 93 million miles away. So, the Sun’s light takes about 8.3 minutes to reach us. This means that we always see the Sun as it was about 8.3 minutes ago.
Read the rest at: spaceplace.nasa.gov/light-year/en/
NASA SciJinks – What’s A Solstice?
Astronomy has been important to people for thousands of years. The ancient construction known as Stonehenge in England may have been designed, among other purposes, to pay special honor to the solstices and equinoxes. These are the times and locations during Earth’s journey around the Sun that we humans have long used to mark our seasons.
Caption: Here is a guess at how Stonehenge might have looked about 2400 BC. At dawn on the Summer Solstice, the rays of the Sun would have shone straight through what is called the “slaughter stones” to exactly strike the “altar stone” in the center.
But what is the solstice exactly?
It has to do with some imaginary lines on our planet. These lines are important, because they help people navigate and measure time.
The equator is an imaginary line drawn right around Earth’s middle, like a belt. It divides Earth into the Northern Hemisphere and the Southern Hemisphere.
Read the rest at: scijinks.gov/solstice/
About NASA Space Place
With articles, activities, crafts, games, and lesson plans, NASA Space Place encourages everyone to get excited about science and technology. Visit spaceplace.nasa.gov (facebook|twitter) to explore space and Earth science!
