Earth our planet

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Every time on this page is now worked out in Vilnius, in local time. Pick another city and the page recalculates the times, heights and visibility for it.

Earth today in Vilnius

Why the day is this long: the tilted axis

The drawing shows Earth today, lit from the left. The axis leans 23.44°, and today the Sun stands 7.3° south of the equator, so the southern hemisphere is turned further towards it. The line is the latitude of the city Vilnius (54.7°): the part of it in sunlight is the day, the part in shadow the night. The more the axis leans towards the Sun, the longer the sunlit part.

Day length through the year

Every day of 2026 in Vilnius: from 7 h 14 min in December to 17 h 18 min in June. At the equinoxes the day lasts about 12 hours everywhere on Earth; the nearer the pole, the steeper the curve.

Where Earth is on its orbit

Earth's orbit seen from above the north pole: the gold dot is Earth today. The four positions are the equinoxes and solstices. The axis keeps pointing to the same place in space (towards the Pole Star), so over the year first one hemisphere and then the other is turned towards the Sun. The orbit is almost a circle: perihelion (147.1 million km) and aphelion (152.1 million km) differ by only about 3%.

Equinoxes and solstices

Earth seen from the Moon

From the Moon, Earth shows phases too, only reversed: when we have a new Moon, a "full Earth" hangs in the black lunar sky, and at full Moon Earth would look almost completely dark from there. Right now the Moon is 5% lit as seen from Earth, and Earth is 95% lit as seen from the Moon. The top row is the Moon as we see it, the bottom row Earth as someone standing on the Moon would see it on the same day.

From the Moon, Earth looks nothing like the Moon does from here. It spans almost 2°, about 3.7 times wider than the lunar disc we see, and covers roughly 13 times more sky. Clouds and oceans also reflect far more light than the dark lunar rock, so a 'full Earth' in the lunar sky shines several dozen times brighter than our full Moon.

Earth's phases are the opposite of the Moon's: at new Moon an observer on the Moon sees a full Earth, at full Moon an almost dark one. That light is the faint grey glow on the dark part of a thin crescent Moon, called earthshine; Leonardo da Vinci was the first to explain it. Because the Moon always keeps the same face towards us, from its near side Earth hangs almost still in the sky, wobbling only slightly with libration while it spins and runs through its phases.

Moon phase today →

The seasons

Seasons do not happen because Earth swings closer to the Sun in summer. They come from the tilt of its axis, 23.44° from upright relative to the orbit. The axis keeps pointing at the same spot in the sky (close to the North Star) all year, so for half the year the northern hemisphere leans towards the Sun and for the other half the southern one does. A higher Sun sends its light down more steeply and for longer each day, and that is summer.

The June solstice (around 21 June) brings the longest day to the northern hemisphere and the December solstice (around 21 December) the shortest; at the equinoxes in late March and late September day and night are nearly equal everywhere. In the southern hemisphere it all runs the other way round: Christmas in Sydney is a summer holiday.

Sunrise and sunset →

Day, night and the length of a day

Earth turns once on its axis in 23 h 56 min 4 s, the sidereal day, measured against the distant stars. The solar day, from noon to noon, is 24 hours on average: in that time Earth also moves along its orbit and has to turn about one degree more before the Sun is back in the south.

How long the day lasts depends on latitude and season. On the equator it stays close to 12 hours all year; the further from it, the bigger the swing. In London the June day lasts more than 16 hours and the December one under 8. Beyond the polar circles the Sun does not set in summer and does not rise in winter. Earth's spin is also very slowly winding down: tides raised by the Moon brake it by a couple of milliseconds per century, and timekeepers have added an occasional leap second since 1972.

The orbit and the year

Earth's average distance from the Sun is 149.6 million km. This is the astronomical unit (AU); sunlight covers it in about 8 minutes 20 seconds. The orbit is slightly stretched: Earth is closest to the Sun (perihelion) in early January, at about 147.1 million km, and furthest (aphelion) in early July, at about 152.1 million km.

Earth travels along its orbit at 29.8 km/s on average and completes one lap in 365.256 days. A calendar year has 365 days, so every fourth year gets 29 February; without it the calendar would drift almost a month away from the seasons in a century.

Earth

Earth is the third planet from the Sun and the largest of the four rocky planets, though only the fifth largest in the Solar System. It is the only place known to host life and the only planet with liquid water standing on its surface: the global ocean covers about 71% of the surface and holds 97% of all of Earth's water.

Inside, Earth is layered like an onion: a solid iron-nickel inner core, a liquid outer core, a thick mantle and a thin crust, about 30 km deep on average under the continents and only around 5 km under the oceans. Its plates drift about as fast as fingernails grow, raising mountains and setting off earthquakes. Earth is also the densest planet in the Solar System, 5.51 g/cm³ on average.

Earth seen from space

The first photograph of Earth from space was taken on 24 October 1946 by a movie camera on a V-2 rocket at about 105 km: grainy black-and-white cloud tops. On 24 December 1968 Apollo 8 astronaut Bill Anders, orbiting the Moon, took 'Earthrise', the blue Earth rising over the grey lunar horizon. On 7 December 1972 the Apollo 17 crew photographed the 'Blue Marble'.

On 14 February 1990 Voyager 1 turned round from about 6 billion km and photographed Earth as the 'Pale Blue Dot', smaller than a single pixel. Since 2015 NASA's EPIC camera on the DSCOVR spacecraft, parked 1.5 million km away towards the Sun, has sent back pictures of the whole sunlit face of Earth every day. And people have lived on the International Space Station continuously since November 2000; you can watch it cross the sky above your own city with the naked eye.

Atmosphere and magnetic shield

Earth is wrapped in an atmosphere of 78% nitrogen, 21% oxygen and about 1% argon, carbon dioxide and other gases. It blocks most of the Sun's harmful radiation (the ozone layer takes out ultraviolet), and burns up most meteoroids before they reach the ground, which we see as shooting stars.

The liquid iron-nickel outer core and the planet's fast spin generate a magnetic field that steers the solar wind round the planet. When the Sun throws out a stronger burst of particles, the field shakes: that is a geomagnetic storm, and particles pouring in near the magnetic poles make the air glow as auroras. Over geological time the magnetic poles have flipped many times, on average about every 300,000 years but very irregularly.

Geomagnetic storm today →

The name and its history

Earth is the only planet not named after a Greek or Roman god. The English word is about a thousand years old and comes from Old English and Germanic words that simply mean 'the ground', much like Latin 'terra' or Lithuanian 'žemė'.

The ancient Greeks knew Earth was round some 2,500 years ago: its shadow on the Moon during a lunar eclipse is always curved, and new stars climb above the horizon as you travel south. Around 240 BC Eratosthenes compared the Sun's shadows at Syene (Aswan) and Alexandria and worked out Earth's circumference remarkably well.

Earth in numbers

The other planets