Sunlight is the primary illuminator. Its spectrum is a familiar rainbow with maximum emittance in a color that most of us would call yellow-green — light of wavelength around 550 nanometers. Read more
Aristotle famously claimed that nature abhors a vacuum. True, air does rush into the space from which air has been evacuated, but not because nature has feelings of any kind about the vacuum. Read more
Where is ET? After nearly 50 years of searching for intelligent signals from space, astronomers have yet to receive a single verifiable signal of intelligent origin. Read more
Water vapor is the gaseous form of water that exists in the atmosphere along with nitrogen, oxygen and other minor gases such as argon and carbon dioxide. Read more
Equilibrium is a state of balance of opposing actions which is central in virtually everything that happens, from basic physics to dance and the arts, economics and social ideologies. Read more
Helium is No. 2. It is the second-lightest element on the periodic table with atomic number of two. Read more
Since the development of MRI scans from the first crude machines in the 1970s, the technology has become more efficient. Read more
The Standard Model is what physicists call the current theory of fundamental particles and their interactions. Read more
Feeling tired today? Most of us grow more weary as the day goes on and as the years pass. We say we are out of energy or getting low on energy, which is a fact. Read more
What is it that gives numbers their power? Read more
Clouds come in all shapes and sizes, but they are usually flat on the bottom. Read more
The aurora borealis, or northern lights, is a common sight at north polar latitudes. The name aurora borealis comes from Latin and Greek. Read more
Outside the window, 7 miles up, the wings of the jet airliner slice through the invisible air that seems magically to keep it aloft. It reminds me that we are immersed in Earth’s invisible atmosphere all of the time. Read more
The names of the 12 months that make up our Western calendar are so familiar that we do not think much about where they came from. Read more
All paint inside a can is black until the can is opened. Strange as it might seem, it is true. What we see as color is a matter of perception, intrinsic properties of an object and the light that illuminates it. Read more
The calendar is such a basic thing that we take it for granted. It consists of 52 weeks of seven days, plus one extra day, for a total of 365 days. Read more
Earth’s gravity creates tidal forces on the moon that keep it locked with one side always facing Earth. This is why we always see the same face of the moon and never see the backside. Read more
Earth is a unique planet in the solar system, and may be the only one of its kind anywhere. Read more
Zero, nothing, zilch, nada? The number zero is a misunderstood enigma. Its place in our number system is relatively recent, appearing much later than the Arabic numerals we use to display number digits. Read more
A word from Captain Obvious: The sun rises in the east and sets in the west. Read more
Although we cannot measure “life” directly, astronomers have confidence that soon we will be able to reliably detect the chemicals of life such as oxygen, methane and nitrogen in the atmospheres of distant planets. Read more
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