What Would Happen If You Stargazed At the North Pole and Which Stars and Constellations Would You See?

If you were looking at stars from Earth’s North Pole, the terrestrial globe would line up precisely with the celestial globe. Your celestial horizon would mirror the celestial equator. The North Star would be at your zenith, straight above your head. All the other stars in the northern hemisphere of the celestial sphere would appear … Read more

What Are Constellations, How Did Constellations Get Their Names, and How Many Constellations Are There?

Constellations are simply groups of stars that people have named for the sake of convenience. People have been mapping constellations for thousands of years, usually naming them after mythological characters or common items that the group of stars resembles. For instance, the constellation Leo looks like a seated lion. If you were to connect the … Read more

How Do Astronomers Locate Stars On a Celestial Globe Using Declination and Right Ascension?

A celestial globe is marked with imaginary vertical and horizontal lines called declination (dec) and right ascension (RA). These lines correspond to latitude and longitude lines on a terrestrial globe. Just as you can locate a town by finding the intersection of its latitude and longitude, Sonora, Texas, sits approximately at 30° north latitude and … Read more

What Is Right Ascension and How Do Astronomers Determine a Star’s Right Ascension Using the Celestial Equator?

Right ascension, or RA for short, is the astronomical term for the location of an object on the celestial sphere when using the equatorial coordinate system. On the terrestrial globe we use longitude lines to express east-west location on Earth. The prime meridian and the International Date Line are the imaginary vertical lines splitting Earth … Read more

How Is a Star’s Declination Determined and How Do Astronomers Use Declination To Locate a Star In the Sky?

Declination (dec) on the celestial globe is like latitude on the terrestrial globe. The celestial equator mirrors Earth’s equator, halving the sphere into northern and southern hemispheres at 0°. The degrees of lines of declination increase north and south to 180° at each celestial pole, just like latitudes increase to 180° at the terrestrial North … Read more

How Is Temperature Measured In Space and Who Invented the Kelvin Scale For Temperature?

Astronomers can measure temperature in space by studying various electromagnetic radiation waves. In the United States, the Fahrenheit (F) scale is usually used to measure temperature. Most of the rest of the world uses the Celsius (C) scale. Scientists, however, use the Kelvin (K) scale, also known as absolute temperature. In 1848, Lord Kelvin, also … Read more

What Is Einstein’s Theory of Special Relativity and When Was the Theory Proposed By Albert Einstein?

While Isaac Newton’s laws of motion and gravity still have validity as a working model for basic astronomy, physicists rely on Albert Einstein’s complex relativity theories in their advanced work. The special theory of relativity, or STR for short, is the physical theory of measurement in inertial frames of reference proposed in 1905. In Einstein’s … Read more

Who Discovered Microwaves, Where Do Microwaves Come From, and How Are Microwaves Important In Astronomy?

Microwaves are not only found in ovens. In 1964, scientists Arno Penzias and Robert Wilson recorded microwaves emanating from every direction in the universe. Penzias and Wilson determined that their source was probably the entire universe. The waves came from everywhere. The only source that can be considered everywhere at once is the universe, if … Read more

What Are Celestial Objects, Where Do They Come From, and What Does the Word Celestial Mean In Latin?

Unless you are blinded by the bright lights of a city, the nighttime sky will show you bright lights of its own. The lights in the sky are objects emitting electromagnetic waves that we see as light. Lumped together, these objects, mostly stars, planets, satellites, comets, galaxies, and meteors, are often called celestial objects, or … Read more

How Dangerous Is Radiation and Are All Types of Radiation Dangerous or Hazardous To Our Health?

There are several types of electromagnetic radiation such as, radio waves, infrared light, visible light, ultraviolet light, and X-rays. Some radiation from elements can be deadly. The bombs that the United States dropped on Hiroshima and Nagasaki, Japan, at the end of World War H, were hydrogen and plutonium bombs, respectively. The radiation from other … Read more

What Is a Radio Telescope and How Do Radio Telescopes Help Astronomers Detect Objects In the Universe?

The word “telescope” generally refers to an optical telescope. But instruments designed to collect radio waves are called radio telescopes or radio dishes. Radio telescopes are basically directional radio antenna used in radio astronomy. Radio telescopes operate in the radio frequency portion of the electromagnetic spectrum where they can detect and collect data on objects … Read more

What Are Infrared Rays and Why Do Astronomers Use Infrared Telescopes To Detect Objects In the Universe?

Infrared rays are long, heat-intensive wavelengths that we cannot see. Telescopes outfitted with heat-sensitive reflectors, instead of mirrors or lenses, gather infrared rays, which are reproduced visually by special photographic equipment. The infrared image of an object is similar to what you see if you put your hand against a very cold window. An outline … Read more

How Can An Object Emit More Than One Type of Radiation and Which Animals Can See Ultraviolet Radiation?

Many objects usually emit more than one type of radiation simultaneously. For instance, the Sun radiates everything from gamma rays to radio waves. People emit radio waves, but we can’t detect those waves without the proper receiving equipment. You’d have to use a radio telescope to do so, but all the other radio waves bouncing … Read more

What Are Radio Waves and What Do Radio Waves Have To Do With Radios and Astronomy?

Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves certainly have a lot to do with radios and astronomy. People cannot see radio waves without re-creating them in a visual format, such as by electronically digitizing the waves in a computer, which in turn … Read more

Why Is Electromagnetic Radiation Described As Waves and Rays and What Is The Difference Between Them?

All radiation travels outward from its source in a wave-like pattern. The term ray is commonly used to describe the rapid, short waves of the upper part of the electromagnetic spectrum: gamma rays, X rays, ultraviolet rays, light rays, and infrared rays. A ray is the straight line along which the waves travel. Slower radiation, … Read more

What Is a Light Year and How Long Does the Light From Our Closest Star Alpha Centauri Take To Reach Earth?

Perhaps the most common measure of space is the light-year. Strangely enough, a light-year can measure both time and space. Many people believe that time and space are inseparable, simply two sides of the same coin. It takes time for light to travel. Light’s unvarying speed in space is about 186,000 miles (297,600 km) per … Read more

What Is a Parsec, How Long Is a Parsec, and Who Invented the Parsec As a Unit of Measurement?

A parsec (pc) is a measure of incredibly large astronomical distance. The word comes from the phrase parallax second. Parallax means the change in a star’s relative position in the sky when viewed from different places, and second refers to the smallest measurement of the change, stars move in arcs measured in seconds. Imagine a … Read more

What Is the Electromagnetic Spectrum and What Are the Different Types of Electromagnetic Radiation Called?

The electromagnetic spectrum is the scientific name for all of the types of known radiation in the universe. From shortest (highest frequency) to longest (lowest frequency) wavelengths, they are: Gamma rays, X rays, ultraviolet rays, visible light rays, infrared rays, and radio waves, which include microwaves, television and FM radio waves, shortwaves, and AM radio … Read more

When Was the First Telescope Invented and How Did Hans Lippershey Invent the First Optical Telescope?

At the beginning of the seventeenth century, Hans Lippershey, a Dutch eyeglass maker, discovered that when he looked through two lined-up lenses at different ends of a long tube, distant objects appeared closer and larger. He was probably not the only one to make this discovery, but his name has come down through history. Lippershey … Read more

How Did Astronomical Telescopes Evolve To Become Bigger and More Powerful To See Deeper Into Space?

Galileo built many telescopes, each more powerful than the last, and in 1609 he was the first to use the instrument, called “Galileo’s ladder”, to study the sky. The great astronomer Sir Isaac Newton modified Galileo’s telescope by using mirrors instead of lenses. A musician and amateur astronomer named William Herschel, who discovered the planet … Read more

What Factors Determine the Power of an Optical Telescope and Why Is the Diameter of the Lens Important?

The size of the objective lens in a refracting telescope, or the primary mirror in a reflecting telescope, and the distance the light travels through the telescope’s tube are the most important elements in determining the power of the telescope. The diameter of a lens or mirror is called the aperture; the larger the aperture, … Read more

Who Was Galileo Galilei and Why Is the Italian Astronomer the Father of Modern Observational Astronomy?

Galileo Galilei seemed to be larger than life. Born in Pisa, Italy, in 1564, at the culmination of the Renaissance, Galileo was not just the first person to focus a telescope on the stars; he also turned the view of the world upside down. Galileo was a master of astronomy, mathematics, physics, philosophy, and publicity. … Read more

When Did Polish Astronomer Nicolaus Copernicus Propose That the Earth Rotated Around the Sun and Why?

The acceptance of the fact that Earth rotated around the Sun was a long time coming. In 1543, the Polish astronomer Nicolaus Copernicus published De Revolutionibus, which stated that the planets revolved around the Sun. His theories, however, disagreed with the teachings of the Roman Catholic Church, and the church was the most powerful social … Read more

How Did Early Astronomers Distinguish One Star From Another and Map the Locations of Stars In the Sky?

Besides mapping the locations of stars in the sky, astronomers also determined which stars were brighter than others. The Greek astronomer Hipparchus, a predecessor of Ptolemy, first classified stars according to their brightness. He listed six categories of brightness by magnitude. Magnitude defines how bright the stars appear to be from Earth. A star’s magnitude … Read more

How Did Astronomy Begin and Why Did Claudius Ptolemy Believe That the Earth Was the Center of the Universe?

Before the invention of the telescope in the early seventeenth century, astronomy was based on observations made by the naked eye. First, people mapped the positions of stars and planets in the sky. Most cultures had their own systems for mapping the sky, but astronomy as we know it today has its roots in classical … Read more

What Is Astronomy, What Does Astronomy Mean In Greek, and Why Is the Study of Astronomy Important To Us?

Astronomy is the study of matter and processes that exist primarily beyond Earth’s atmosphere. It covers the whole universe, the heavens, the celestial sphere, from microscopic atoms to the vast cosmos. Astronomers study the heavenly or celestial bodies such as planets, stars, comets, galaxies, nebulae, and intergalactic material to determine how they formed, how they … Read more

Where is the Planet Vulcan Located, How did Vulcan Get its Name, and Does the Planet Vulcan Really Exist?


In 1845, some astronomers believed that the only explanation for Mercury’s confusing and erratic orbit of the sun would be the presence of gravitational pull from an unseen nearby planet, which they named “Vulcan.” French mathematician Le Verrier, who came up with the hypothesis to explain Mercury’s orbit, died in 1877, still convinced of having … Read more

What Is A Solar Flare?

A solar flare is a large explosion in the Sun’s surface that can release intense amounts of radiation. The radiation emitted by solar flares can affect the Earth’s ionosphere and disrupt radio communications on earth. Solar winds are the steady flow of electrically charged particles sent out by the sun. Did you know that there … Read more

How Often Do Asteroids Hit the Earth?

Asteroids are actually very tiny planets which revolve in orbit around the sun. Thousands have been seen by astronomers and many have been named. But new asteroids are being discovered almost daily. Sometimes, because of the attraction of other planets, these asteroids change their orbit and collide with other asteroids. The fragments that break off … Read more