Even though Venus is the closest planet to Earth, it is often eclipsed in popular culture by another neighboring planet, Mars. Though Mars has similar surface conditions to Earth, Venus appears more like Earth's twin -- similar in size, density and mass. Venus may be Earth's celestial neighbor, but it still takes a spacecraft over a year to reach the planet, whose orbit takes it closer to the sun.| Sciencing
Days are longer in summer and shorter in winter because the earth spins on an axis that’s tilted. As the earth revolves around the sun once per year, the angle at which the planet receives sunlight changes. The axis tilt changes the position of the sun in the sky, making it appear for more or fewer hours, depending on the season and the latitude, or distance from the equator.| Sciencing
Tides are the constant rising and falling of sea levels across the globe. Newton’s laws of gravity say that two bodies in the universe are attracted to each other by gravitational pull. The laws express how the mass and distance between those bodies affect the attraction. The sun and moon both hold sway over movements on Earth, and the attraction between all three -- sun, moon and Earth -- affect the tides.| Sciencing
Four seasons -- autumn, winter, spring and summer -- occur throughout the year. Each hemisphere experiences an opposite season. For example, the winter season in the northern hemisphere is summer in the southern hemisphere. The seasons are caused by the tilt of the Earth's axis as it orbits the sun.| Sciencing
Most nocturnal animals have the ability to see well in the dark, which makes it easier for them to sneak up on unsuspecting prey. Their pupils dilate to allow maximal light exposure. Animals with good night vision also have many light-receptor cells called rods that help them control their eye sensitivity to light. Most can't see as well during the day and can't see color.| Sciencing
The moon is Earth's longtime, familiar companion, the story of when and how it got there is actually a bit of an unanswered question in astronomy.| Sciencing
Sciencing offers informative articles, instructional guides, and cutting-edge answers to pressing questions about science, engineering, and mathematics.| Sciencing
Informative articles on telescopy, orbital mechanics, and the observation and study of the solar system, the galaxy, and the visible universe beyond.| Sciencing
Explore the hard sciences through stories derived from every discipline including discussion of theory, experimentation, and empirical fact.| Sciencing