Articles About Earth (36)
Earth Is Tilted
When an object the size of Mars crashed into the newly formed planet Earth around 4.5 billion years ago, it knocked it over and left it tilted at an angle.
Magnetic Declination
A compass needle doesn't point to the geographical North Pole but to magnetic north. Did you know that it usually doesn't point to the magnetic North Pole either?
March Equinox
At the March equinox, the Sun crosses the equator from south to north. Explanation and 2026 equinox date.
June Solstice 2026
The June solstice is the longest day of the year in the Northern Hemisphere and the shortest day in the Southern Hemisphere.
September Equinox
The Sun shines directly on the Equator on the September equinox and the length of day and night is nearly equal, but not quite.
December Solstice
December solstice marks the shortest day north of the equator and the longest day in the south.
Earth Is Speeding Up
Our home planet has been spinning unusually fast lately. 2020 had some of the shortest days on record.
The Earth Keeps Good Time
While we are constantly trying to build a better clock, it’s easy to forget there’s a very accurate timekeeper right under our feet: planet Earth.
How Long Is a Day on Earth?
In terms of solar time, most days are a little longer than 24 hours. Exact day length for today and yesterday.
The Future of Leap Seconds
Organizations and individuals have for many years argued about abolishing leap seconds for good.
What Are Leap Seconds?
Every now and then a leap second is added to Coordinated Universal Time (UTC) in order to synchronize clocks worldwide with the Earth's rotation.
Will a Negative Leap Second Be Needed Soon?
Our planet is currently spinning, on average, ahead of schedule. This might lead to a negative leap second.
What Is the Antumbra?
The antumbra is the lighter part of a shadow that forms at a certain distance from the object casting the shadow. It is involved in annular solar eclipses and planet transits.
What Is the Penumbra?
The penumbra is the lighter outer part of a shadow. The Moon's penumbra causes partial solar eclipses, and the Earth's penumbra is involved in penumbral lunar eclipses.
Shadow Science
There are three kinds of shadows that produce eclipses.
What Is the Umbra?
The umbra is the dark center portion of a shadow. The Moon's umbra causes total solar eclipses, and the Earth's umbra is involved in total and partial lunar eclipses.
The Equator Divides Earth in Two
The equator is an imaginary line dividing Earth into the Northern and Southern Hemispheres. It is located halfway between the North and South poles.
What Are Longitudes and Latitudes?
Cartographers and geographers divide the Earth into longitudes and latitudes in order to locate points on the globe.
Is the Greenwich Meridian in the Wrong Place?
Why does a GPS device not show 0 degrees of longitude at the line marking the prime meridian in Greenwich, London, UK? Is it wrong—or just different?
The Northern and Southern Hemispheres
The Northern Hemisphere spans from the equator to the North Pole, while the Southern Hemisphere extends from the equator to the South Pole.
Earliest Sunset Not on Winter Solstice
Why doesn't the year's earliest sunset occur on the winter solstice, even though it is the shortest day of the year in terms of daylight?
What Is Earthshine?
Earthshine is a dull glow that occurs when the Sun’s light reflects off the Earth's surface and illuminates the unlit portion of the Moon.
Equation of Time
The difference between the time measured by the Sun and the time measured by our clocks is known as the equation of time.
Astronomical Glossary - Terms & Definitions
What do astronomers really mean when they use those technical terms?
Altitude & Azimuth: The Horizontal Coordinate System
Learn how to use altitude (elevation) and azimuth angles to locate any object in the sky, such as stars, planets, satellites, the Sun, or the Moon.
Midnight Sun
The Midnight Sun is where the Sun never sets over a period of 24 hours or more. It occurs in polar regions during summer.
What Causes Seasons on Earth?
Seasons change because Earth's rotational axis tilts away or towards the Sun during the course of a year.
The Moon Effect
Does the Moon really affect our sleep, behavior, and personality?
What Causes Tides?
The gravitational pull of the Moon and the Sun makes the water in the oceans bulge, causing a continuous change between high and low tide.
Earth: The Living Planet
Earth is the largest of the Solar System’s rocky inner planets.
99% of Earthlings See Sunlight on July 8 (And on Other Dates, Too)
Our Sun data confirm an internet meme claiming 99% of the world’s population gets sunlight at 11:15 UTC on July 8. But does it happen on other dates, too?
99% Of Us See Daylight at This Moment (Or Do We?)
Is it really true that 99% of the world's population see daylight at 11:15 UTC on July 8?
Earth Slows Down, but Remains Unpredictable
Earth rotation update, April 2024: following a recent run of the shortest days ever recorded by atomic clocks, Earth’s rotational speed may be slowing.
The End of the Leap Second?
A resolution passed on November 18, 2022, means the world may be moving closer to getting rid of leap of seconds.
Dec 6: Minute of Global Darkness
There's a moment each year when almost 9 in 10 people worldwide experience night.
Earth Sets New Record for Shortest Day
On June 29, 2022, Earth recorded its shortest day since scientists began using atomic clocks to measure its rotational speed.