The first few things you would notice if you could stand on Venus would probably be the heat, the relatively constant calm weather, and the orange-colored rocks and dry dirt at your feet. In general, it might feel like you were in one of the Great Plains states in the middle of a billion-year-long drought. […]
Nebulae is the Latin word for clouds, nebula is the singular form. Many nebulae or stars form from the gravitational collapse of gas in the interstellar medium. As the matter collapses under its own weight, huge stars may form in the center, and their ultraviolet radiation ionises the surrounding gas, making it visible to the […]
Why Do the Planets In Our Solar System Have Elliptical Orbits and What Is a Planet’s Aphelion and Perihelion?
Ellipses are oval shapes. In more technical terms, an ellipse is a plane curve that results from the intersection of a cone by a plane in a way that produces a closed curve. All planets orbit the Sun in ellipses, not perfect circles. This is because their trajectories are affected by the gravitational forces of […]
What Is a Planet, How Many Different Types of Planets Are There, and What Does the Word Planet Mean In Greek?
Many qualities define a planet, but not all planets meet all criteria. A planet is a body that revolves around a star. It does not generate light, but reflects the light of a star. While stars appear as points of light through a telescope, planets look like disks. The word planet comes from the Greek […]
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 […]
When Did the Planets In the Solar System Form and How Long After the Big Bang Were the Planets Created?
We know that Earth came into existence about 4.6 billion years ago, and it is most likely that the other planets formed at about the same time, just after the Sun started shining some 5 billion years ago. Almost all meteorites date to around this same time, which substantiates this theory of when the planets […]
The Sun’s corona, or outer layer of atmosphere, can only be seen during a solar eclipse. At other times, the brightness of the Sun makes the corona disappear from sight, just as the Sun’s light makes it impossible to see stars in the daytime. Astronomers artificially block the Sun’s surface with special equipment, so as […]
Meteorites can fall anywhere on Earth. Depending on where they fall and their size, they could cause considerable damage. But this has rarely happened. Most meteorites weigh only 2.2 pounds, or about 1 kg, and most break into smaller pieces or vaporize on impact. The most destructive meteorite of all time is purely hypothetical. Many […]
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, […]
Why Did Cosmonauts Fly Missions In Their Underwear and When Did Cosmonauts Start Wearing Space Suits?
Cosmonauts wear space suits now, at least during takeoff, landing, and docking. Originally, space suits were not required, and some cosmonauts flew in their underwear. But on June 29, 1971, when the three cosmonauts in Soyuz 11 undocked from the space station Salyut 1, an air release valve suddenly opened. Without the life-support systems of […]
Mercury, Venus, Earth, and Mars, the first four planets in order from the Sun to the asteroid belt, are called the inner planets or terrestrial planets. The inner planets all have hard, solid surfaces, terra means “earth” in Latin. They share a few other characteristics of Earth that partially result from their proximity to the […]
By studying galactic light that originates 300 million light-years away, astronomers can look at galaxies that are 300 million years younger than the Milky Way. The light we see today started traveling 300 million years ago, so it represents the source galaxy as it was 300 million years ago. Galaxies at different distances portray different […]
NASA’s Gemini 3, carrying Virgil Grissom and John Young, was launched on March 23, 1965. It was the first manned Gemini flight, the seventh American flight into space, and the 17th manned spaceflight from Earth of all time. The test flight gave the astronauts a chance to try out maneuvers necessary to get to and […]
How Is Pluto’s Orbit Around the Sun Irregular and What Is the Planet Pluto’s Perihelion and Aphelion?
The planet Pluto’s perihelion, or closest point to the sun is 4.4 billion miles (7 billion km) from the Sun. Its aphelion, or farthest point is 7.4 billion miles (11.8 billion km). This usually makes Pluto the farthest planet from the Sun, but not always. Pluto’s orbit crosses the path of Neptune’s orbit, and for […]
What Happens When a Star Becomes an Old Star and What Causes a Helium Flash In the Core of a Red Giant?
The core of a red giant or super giant, also known as an old star, is mostly helium, with an outer shell of burning hydrogen. The helium contracts while the hydrogen expands. The star grows brighter and much bigger as the hydrogen escapes into space as radiation. Expansion cools the shell, but contraction heats the […]
Seismographic instruments placed on the Moon by the Apollo astronauts determined that the satellite is mostly solid, with a crust, mantle, and core. Scientists are not sure what the core is made of, or whether it is at least partially molten, or melted. We do know, however, that it is made of the Moon’s densest […]
A galaxy is a loose formation of between 1 million and 1 trillion stars, dust, and gases. These stars, dust, and gases are drawn together in clusters by their forces of gravity, much in the same way as our solar system is held together by the gravity of the Sun and the planets. It is […]
Why Are Galaxies In the Universe Usually Found In Clusters and Why Are Isolated Galaxies Rarely Found?
Most galaxies in the universe are grouped together in clusters because of their mutual gravitational attraction. These clusters contain anywhere from just a few to thousands of galaxies. Within clusters, galaxies orbit each other at speeds of about 600 miles per second. In turn, galactic clusters often come in groups called superclusters, which can be […]
How Big Is the the Great Red Spot On Jupiter and Is the Great Red Spot On the Planet Jupiter Permanent?
The Great Red Spot on Jupiter is a persistent anticyclonic storm that is about 24–40,000 km × 12–14,000 km, and is large enough to contain two or three planets the size of Earth. We don’t know whether or not the Great Red Spot will disappear for good one day. Storms on Earth sooner or later […]
How Large Are the Rings Around the Planet Saturn and How Far From the Surface of Saturn Do the Rings Extend?
The whole system of rings, gaps and all, begins about 40,000 miles (64,000 km) out from Saturn’s equator and ends 290,000 miles (464,000 km) from the surface. That’s 250,000 miles (400,000 km) of rings and gaps. The particles are not spread out on a single plane, but the rings are very thin. Compared to the […]
Jupiter has sixteen known satellites, but astronomers believe there could be more. The discovery of the four largest, Ganymede, Callisto, Io, and Europa, is credited to Galileo, who recorded them in 1610. The average diameter of the Galilean moons measures 2,540 miles (4,230 km), whereas the average diameter of the other Jovian moons is a […]
What Is a Solar Prominence, What Do Solar Prominences Look Like, and How Big Do Solar Prominences Get?
Solar prominences appear as flaming arches at the limb, or edge, of the Sun’s disk. Electrically charged gases in solar prominences come from the magnetic fields around sunspots. Prominences last for weeks or even months, and arc tens of thousands of miles into the Sun’s chromosphere. When a solar prominence is viewed from a different […]
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 […]
The USSR launched five missions (Zond 4-8) between 1968 and 1970, apparently as tests for a manned Moon landing, but the exact purpose of the missions has never been fully revealed to the scientific community. The Soviet lunar program was dropped 3 years after U.S. astronauts Armstrong and Aldrin made it to the Moon and […]
Not all meteors come in showers. Under clear, dark skies, you should be able to see five or six meteors a night, if you stay up all night. During an annual shower, or a storm, you can see hundreds a night. Meteor showers occur as Earth travels through the orbital path of a specific comet. […]
What Is The Straight Wall On the Moon and How Did the Topographical Feature On the Moon Get Its Name?
Neither straight, nor a wall, the Straight Wall is a fascinating topographical feature in the Moon’s southwest quadrant on the eastern border of the Mare Nubium. It looks like a straight, precise wall, but it is a fault, or geological crack in the surface, with a 1,000-foot (300-m) drop on its west side. Because of […]
Pluto is very dense, so astronomers believe it is mostly rock, unlike its neighboring gas giants. It seems to be covered with ice, perhaps composed of methane and nitrogen. Bright and dark areas appear on the surface, and Pluto has polar ice caps. Most astronomers expect that Pluto’s internal structure is differentiated, with the rocky […]
Try this exercise to visualize the universe as astronomers see it. Take a deflated balloon and draw small stars on it with a marker. The stars represent galaxies. Label one the Milky Way, for our galaxy. Now, blow up the balloon. The growing balloon is similar to the expanding universe. You will see how the […]
Who Built the Saturn Rockets For the Apollo Space Missions and How Many Stages Did Saturn Rockets Have?
Saturn rockets, based on missiles developed by the U.S. Department of Defense, launched most of the Apollo missions. The Saturn rocket boosters were developed by a team of German rocket scientists led by Wernher von Braun to launch heavy payloads into space. They were originally meant as a military satellite launcher, but they were adopted […]
The universe is a dynamic, evolving organism. It is commonly defined as the totality of everything that exists. It had a beginning, probably a sudden, massive expansion of matter, and it may have an end. We don’t really know. Meanwhile, it grows by means of further expansion; galaxies move farther and farther away from each […]
The planet Neptune has an atmosphere of hydrogen, helium, and methane, just as Uranus does. The methane, which lies in a haze over the planet’s thick cloud cover, absorbs the red end of the spectrum, reflecting the blues. Neptune’s vivid deep azure, however, is a little different from Uranus’s milder aquamarine. Neptune’s atmospheric methane content […]
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, […]
A star’s age or maturity is marked by its location on the main sequence of the Hertzsprung-Russell diagram. Where it first appears on the main sequence, however, depends on its mass. A star with greater mass will be hotter, take less time to mature, and will appear on the upper part of the diagram. A […]
What Is the Titius Bode Law and When Did Johann Bode Plagiarize Johann Titius’s Work On Orbital Systems?
The Titius–Bode law, also known as Bode’s law, is a hypothesis that the bodies in some orbital systems, including the Solar System, orbit at semi-major axes in an exponential function of planetary sequence. Johann Bode published Johann Titius’s planetary spacing equation in 1772 8 years after Titius worked it out, as his own. It was […]
Current theories say the universe’s continued expansion depends on how much physical matter exists in the universe, and we aren’t sure just how much stuff there is. The amount of matter that would keep the universe stable is called omega. Omega is a hypothetical, unknown quantity of matter, but scientists have determined what is likely […]
We are all well acquainted with Earth, but try to think about Earth in the same way you think about the other planets. Earth is the third planet from the Sun, and it orbits in a near-circular ellipse. The planet Earth is about the same size as Venus, and it has the same mass and […]