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Mars, Viking Orbiter Mosaic JB1960
The center of Mars is at latitude 30 degrees north, longitude 270 degrees. NASA's Viking Mission to Mars was composed of two spacecraft, Viking 1 and Viking 2, each consisting of an orbiter and a lander. The primary mission objectives were to obtain high resolution images of the Martian surface, characterize the structure and composition of the atmosphere and surface, and search for evidence of life. The results from the Viking experiments give our most complete view of Mars to date. Volcanoes, lava plains, immense canyons, cratered areas, wind-formed features, and evidence of surface water are apparent in the Orbiter images. The planet appears to be divisible into two main regions, northern low plains and southern cratered highlands. Superimposed on these regions are the Tharsis and Elysium bulges, which are high-standing volcanic areas, and Valles Marineris, a system of giant canyons near the equator. The surface material at both landing sites can best be characterized as iron-rich clay. Measured temperatures at the landing sites ranged from 150 to 250 K, with a variation over a given day of 35 to 50 K. Seasonal dust storms, pressure changes, and transport of atmospheric gases between the polar caps were observed. The biology experiment produced no evidence of life at either landing site. June 1998. View more images of Mars at ScienceSource.com
Beach weather gives us the opportunity to get outdoors, enjoy the fresh air, and soak up some Vitamin D, but also brings concerns about excessive sun exposure. With stronger and more frequent sun comes a higher risk for skin to be damaged by UV rays, making the body more susceptible to skin cancer.
Skin cancer is one of the most common types of cancer. The Skin Cancer Foundation states that more people are diagnosed with skin cancer each year in the U.S. than all other cancers combined. The cause is most often UV rays from the sun or tanning beds. Skin cancer is generally categorized into two groups, melanoma, and nonmelanoma.
Melanoma cancer begins in melanocytes, which are cells that produce skin pigment (melanin) and reside deep within the epidermis (the outer layer of the skin). Melanoma is known to often be more serious than nonmelanoma cancer because it has the tendency to advance and spread rapidly. The number of new melanoma cases are also on the rise. That being said, the ea…
One of the more fun classes in high school was chemistry lab, especially on the days when you made things explode or catch fire...on purpose.
Relive those good old days with our videos of exploding chemistry experiments.Stock Videos of Exploding Chemical Reactions
The Barking Dog experiment and the Rainbow Clock were very popular. But it's hard to beat the surprisingly loud explosion of a nitrogen triiodide explosion when it's touched lightly by a feather.
And no one expects a tiny piece of metal dropped into water to steam, hiss, dance about and eventually explode, but lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and caesium (Cs) do exactly that. Gifts for the Chemistry Geeks
Here's what happens in each reaction:
Let's check what happens if we would drop a pea-size piece of metal in water.Lithium just sizzles on top of the water, but doesn't explode.Sodium floats on top of the water, then ignites with a yellow-orange flame and also doesn't explode…