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Earth will reach its farthest point from the Sun on July 6, a yearly astronomical event known as aphelion. At around 152.1 million kilometres from the Sun, the planet will be about 5 million kilometres farther away than it is in early January.
Yet, despite this greater distance, the Northern Hemisphere will remain firmly in the grip of summer, with no drop in temperatures. The timing surprises many people because it seems to defy common sense. If Earth is farther from the Sun, shouldn't it be cooler? Scientists say the answer is no. The seasons are shaped not by how far Earth is from the Sun, but by the way our planet is tilted as it journeys through space.
Why Earth reaching its farthest point from the Sun won't cool the summer heat
At first glance, it seems obvious that being farther from the Sun should make Earth cooler.
After all, moving away from a campfire makes you feel less warm.But space does not work quite like that.Imagine shining a torch onto a wall. Hold it straight and the light forms a small, bright circle. Tilt the torch and the same light spreads over a much larger area, making it less intense. The Sun behaves in a similar way.During July, the Northern Hemisphere is tilted about 23.5 degrees towards the Sun. Because of this tilt, sunlight strikes the ground more directly and daylight lasts much longer than it does in winter.
Those two factors deliver far more energy to the surface than the small reduction caused by Earth's greater distance from the Sun.That is why cities across Europe, North America and much of Asia continue to experience warm summer days even when Earth is at its most distant point from the Sun.
Isn't it amazing what Earth is doing right now?
Pause for a moment and think about where you are.You are standing, sitting or walking on a planet that is rotating at up to about 1,670 kilometres per hour at the equator while simultaneously orbiting the Sun at an average speed of around 107,000 kilometres per hour.You cannot feel either movement.At this very moment, someone could be relaxing beside a public swimming pool in Spain, Greece or Italy, soaking up the summer sunshine. Thousands of kilometres away, someone in Australia, New Zealand or Argentina may be pulling on a winter jacket before heading to work.They are all travelling through space together on the same planet, moving at incredible speeds, yet experiencing completely opposite seasons simply because Earth is tilted.It is one of the most elegant examples of how precisely our Solar System works.
What is aphelion?
Aphelion is the point in Earth's orbit where it is farthest from the Sun. This year, it occurs on July 6, when Earth will be about 152.1 million kilometres (94.5 million miles) away.The opposite point is called perihelion, which occurs in early January when Earth is about 147.1 million kilometres (91.4 million miles) from the Sun.Although that sounds like a huge difference, it amounts to only about 3.3 per cent of Earth's average distance from the Sun because our planet follows an orbit that is almost circular, not highly elongated.
Does Earth's distance from the Sun matter at all?
Yes, but far less than most people imagine.At aphelion, Earth receives about 7 per cent less solar energy than it does at perihelion because sunlight spreads over a slightly larger area. The Sun also appears around 3 per cent smaller in the sky, although the difference is too small for the human eye to detect.Even so, this slight reduction has little effect on everyday weather.The atmosphere, oceans and land absorb and slowly release heat, acting like a giant thermal reservoir.
This natural buffering smooths out small changes in incoming sunlight, meaning the effect of Earth's distance is largely overshadowed by the planet's tilt.
Why does the Southern Hemisphere have winter in July?
The explanation is beautifully simple.When the Northern Hemisphere tilts towards the Sun, the Southern Hemisphere tilts away from it. As a result, countries such as Australia, South Africa, Chile and Argentina experience shorter days and cooler temperatures while much of Europe, Asia and North America enjoy summer.Around six months later, the situation completely reverses.Interestingly, Southern Hemisphere summer occurs when Earth is actually closest to the Sun. However, because most of the Southern Hemisphere is covered by oceans, which warm and cool more slowly than land, its seasonal temperatures are generally less extreme than many people expect.
Earth even slows down during aphelion
Earth's distance from the Sun also changes the speed at which it travels through space.According to Johannes Kepler's Second Law of Planetary Motion, planets move fastest when they are closest to the Sun and slowest when they are farthest away.Near perihelion, Earth travels at about 30.29 kilometres per second, or nearly 109,000 kilometres per hour. Near aphelion, that falls to around 29.29 kilometres per second, or about 105,400 kilometres per hour.Because Earth moves a little more slowly during this part of its orbit, the Northern Hemisphere experiences the longest season of the year.
Summer lasts almost five days longer than winter.
Why doesn't aphelion fall on exactly the same date every year?
Although aphelion usually occurs between July 3 and July 6, the exact date changes slightly from year to year.Leap years, along with the gravitational pull of the Moon and the other planets, subtly alter Earth's orbit. Over thousands of years, the orientation of Earth's orbit also changes through a process called apsidal precession, causing aphelion and perihelion to slowly drift across the calendar.
A perfectly balanced system, now facing a new challenge
Earth's annual journey around the Sun is a remarkable example of cosmic precision. A planet tilted by just 23.5 degrees, spinning on its axis while racing around the Sun at more than 100,000 kilometres per hour, has produced a stable cycle of seasons that has supported life for millions of years.Today, however, that natural balance is increasingly being disrupted by human-driven climate change. Global warming is not changing Earth's orbit or its tilt, but it is making heatwaves more frequent, raising average temperatures and increasing the likelihood of extreme weather across many parts of the world.So, when Earth reaches its farthest point from the Sun on July 6, remember that the summer heat has very little to do with distance. Instead, it is a reminder that the seasons depend on the remarkable geometry of our planet's tilt, and that the climate we experience today is being shaped not by a changing orbit, but increasingly by the choices humanity makes.
