The Sun. Motion and constellations

06/05/2026

The online simulations of the motion of the sun on this page will help us to learn more about the closest star to Earth, the one that supplies us with the energy that allows life to exist. You will discover interesting details about its movement, the solar ecliptic and the constellations of the zodiac.

This Thematic Unit is part of our Earth Sciences collection

Analemma

Figure-eight curve representing the Sun’s position if observed daily at the same time.

Apparent Motion of the Sun

Sun’s movement in the sky as seen from Earth due to Earth’s rotation and orbit.

Ecliptic

Curved line along which the Sun’s apparent motion occurs as seen from Earth.

Equinox

Time of year when the Sun crosses the celestial equator and day and night are of equal length.

Photosphere

Luminous surface of the Sun that emits most of the radiation we receive.

Solar Corona

Outermost layer of the Sun’s atmosphere, made of plasma and visible during total eclipses.

Solar Declination

Angle between the Sun’s rays and the plane of the Earth’s equator.

Solar Noon

Instant when the Sun crosses the observer’s meridian and reaches its highest point.

Solstice

Time when the Sun reaches its maximum or minimum declination relative to the celestial equator.

Sunspot

Region of the photosphere with lower temperature and intense magnetic activity.

Zenith

Point on the celestial sphere located exactly above an observer’s vertical.

What is the Sun

The Sun, our nearest star, is a gigantic sphere of hot plasma that radiates light and heat in all directions. It is the center of our solar system and provides life and energy to all the planets that orbit it, including Earth.

The Sun is approximately 4.6 billion years old and is estimated to have a lifetime of at least another 5 billion years. Its size is impressive, with a diameter of about 1.4 million kilometers, making it 109 times larger than Earth. Its mass is about 333,000 times that of our planet and it contains more than 99% of the total mass of the solar system.

Studying the Sun is fundamental to understanding how it works and predicting its behavior. Scientists use space and ground-based observatories to study its solar activity, such as sunspots, solar flares and coronal mass ejections, which can affect communications, power grids and navigation systems on Earth.

Chemical composition of the Sun

The Sun is composed mainly of hydrogen (about 74% of its mass) and helium (about 24%), along with traces of heavier elements. At its core, temperatures reach 15 million degrees Celsius and pressures are enormous, allowing nuclear fusion reactions to occur in which hydrogen nuclei combine to form helium, releasing large amounts of energy in the process.

This energy is transported to the surface of the sun through a process known as convection and is then emitted into space in the form of light and electromagnetic radiation at all wavelengths, from gamma rays and X-rays to visible light and even radio waves.

Solar radiation

Solar radiation is essential for life on Earth. It is responsible for photosynthesis in plants, which converts sunlight into chemical energy and provides oxygen to the atmosphere. It is also the main source of heat on our planet, affecting weather patterns and regulating the water cycle.

Motion of the Sun. The solar ecliptic and the zodiac

The movement of the Sun, as seen from Earth, appears to follow a path from east to west due to the Earth’s rotation. In addition, throughout the year, the Sun moves across the sky following a path called the solar ecliptic, due to the Earth’s orbit around the Sun. This annual movement of the Sun causes its position to change daily in relation to the constellations and the horizon. In a broader sense, the Sun also moves in the galaxy, orbiting the center of the Milky Way at a speed of about 220 km/s, completing one revolution in about 225-250 million years.

Analemma

Figure-eight curve representing the Sun’s position if observed daily at the same time.

Apparent Motion of the Sun

Sun’s movement in the sky as seen from Earth due to Earth’s rotation and orbit.

Ecliptic

Curved line along which the Sun’s apparent motion occurs as seen from Earth.

Equinox

Time of year when the Sun crosses the celestial equator and day and night are of equal length.

Photosphere

Luminous surface of the Sun that emits most of the radiation we receive.

Solar Corona

Outermost layer of the Sun’s atmosphere, made of plasma and visible during total eclipses.

Solar Declination

Angle between the Sun’s rays and the plane of the Earth’s equator.

Solar Noon

Instant when the Sun crosses the observer’s meridian and reaches its highest point.

Solstice

Time when the Sun reaches its maximum or minimum declination relative to the celestial equator.

Sunspot

Region of the photosphere with lower temperature and intense magnetic activity.

Zenith

Point on the celestial sphere located exactly above an observer’s vertical.

Explore the exciting STEM world with our free, online, simulations and accompanying companion courses! With them you’ll be able to experience and learn hands-on. Take this opportunity to immerse yourself in virtual experiences while advancing your education – awaken your scientific curiosity and discover all that the STEM world has to offer!

Simulations of motion of the Sun

Diurnal motion of the Sun

The diurnal motion of the Sun is the change of the Sun’s position in the sky due to the rotational motion of the Earth.

Solar ecliptic

The solar ecliptic is the path the Sun describes in the sky. The zodiac is the twelve constellations of the ecliptic.

Constellations of the Zodiac

The zodiac is a belt of the sky with a width of about 8° around the ecliptic. It allows us to locate the Sun, the Moon and most of the planets in their apparent position. It is divided into 12 parts, each of which corresponds to a constellation: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius and Pisces.

Giants of science

“If I have seen further, it is by standing on the shoulders of giants”

Isaac Newton

Johannes Kepler

1571

–

1630

Kepler formulated the three laws of planetary motion, establishing elliptical orbits and the relationship between planetary period and distance from the Sun

“The heavens teach the geometry that nature follows”

Isaac Newton

1643

–

1727

Isaac Newton formulated the law of universal gravitation and the three laws of motion, founding classical mechanics.

“If I have seen further, it is by standing on the shoulders of giants”

Become a giant

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Giants of science

“If I have seen further, it is by standing on the shoulders of giants”

Isaac Newton

Pierre-Simon Laplace

1749

–

1827

Pierre-Simon Laplace developed probability theory and mathematical statistics, and made fundamental contributions to astronomy and celestial mechanics.

“Probability theory is the science of analyzing chance”

Léon Foucault

1819

–

1868

Léon Foucault demonstrated Earth’s rotation with his famous pendulum and measured the speed of light with great precision, revolutionizing experimental optics

“The pendulum does not lie: the Earth moves beneath our feet”

Become a giant

Your path to becoming a giant of knowledge begins with these top free courses

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The Radio Sky II: Observational Radio Astronomy

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The Radio Sky I: Science and Observations

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Our Place in the Universe

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Our Global Ocean – An Introduction Course

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Sensing Planet Earth – Water and Ice

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Sensing Planet Earth – From Core to Outer Space

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Test your knowledge

What do we mean by “movement of the Sun,” and why is it considered an apparent motion from Earth’s perspective?

The so‑called “movement of the Sun” refers to the path it seems to follow across the sky from sunrise to sunset, but in reality this is an apparent motion caused by Earth’s rotation on its axis, which makes the Sun appear to travel from east to west. This phenomenon is essential for understanding the alternation of day and night, geographic orientation and the way sunlight changes throughout the day, and it also serves as the foundation for explaining more complex apparent motions related to Earth’s axial tilt and its orbit around the Sun.

How does Earth’s axial tilt influence the Sun’s apparent path and the length of the day throughout the year?

Earth’s axial tilt causes the Sun’s apparent path to change depending on the season, so in summer the Sun follows a higher and longer arc across the sky, producing longer days, while in winter its path is lower and shorter, resulting in shorter days. This seasonal variation explains why sunlight reaches different latitudes with different intensity and duration, and it underlies phenomena such as solstices, equinoxes and the contrast between hemispheres, all of which stem from the geometry of Earth’s motion.

If the Sun doesn’t actually move around us, why does it look so obvious that it “rises” on one side and “sets” on the other?

It feels so obvious because our immediate reference point is the ground beneath us, which seems completely still, so our brain naturally interprets the changing light as the Sun moving rather than Earth turning. Since Earth’s rotation is smooth and we don’t feel it, what we perceive is the visual effect: the horizon brightens, the Sun appears, climbs, descends and disappears, and even when we know the scientific explanation, the everyday experience still gives the strong impression that the Sun is the one doing the moving.

Why doesn’t the Sun always rise exactly in the east or set exactly in the west? I thought that was fixed.

Although we often say the Sun rises in the east and sets in the west, that only happens precisely on the equinoxes; the rest of the year the sunrise and sunset points shift toward the northeast or southeast depending on the season, because Earth’s axial tilt makes the Sun’s apparent path change slightly every day. That’s why in summer it rises farther north and in winter farther south, and this shift is easy to notice if you watch the horizon over several weeks.

Why can the Sun stay up for days in some places, or not rise at all? It sounds almost impossible.

In regions near the poles, Earth’s axial tilt causes the Sun to remain above the horizon even as the planet rotates, producing the so‑called “midnight sun,” while in the opposite season the Sun never climbs high enough to appear, creating extremely long nights. This isn’t a glitch in the day‑night cycle but a direct consequence of how Earth is oriented relative to the Sun during its yearly orbit, and it explains why polar areas experience such extreme patterns of light and darkness.