Hubble Space Telescope: The Eye in Space That Changed How We See the Universe

There are very few scientific instruments that become famous outside the world of science. The Hubble Space Telescope is one of them. Even people who may not follow astronomy closely have probably seen one of its breathtaking images — colorful clouds of gas, enormous galaxies filled with billions of stars, or tiny points of light representing galaxies billions of light-years away.

But Hubble is far more than a camera taking beautiful pictures of space. It is one of the most important scientific instruments ever built.

A Telescope Above the Atmosphere

The Hubble Space Telescope was launched on April 24, 1990, aboard the Space Shuttle Discovery. It was developed through a partnership between NASA and the European Space Agency and placed in low-Earth orbit.

Putting a telescope in space offered a major advantage.

Telescopes on Earth have to observe the universe through our planet's atmosphere. While the atmosphere keeps us alive, it also distorts incoming light. This is why stars appear to twinkle when we look at them from the ground.

Hubble observes from above most of the atmosphere, allowing it to capture extremely sharp images and detect wavelengths of light that are difficult or impossible to study properly from Earth's surface.

At the heart of Hubble is a primary mirror about 2.4 metres wide. Light collected by this mirror is directed toward scientific instruments that allow astronomers to study distant objects in remarkable detail.

Hubble's Difficult Beginning

Interestingly, Hubble's story did not begin with immediate success.

Soon after the telescope started sending images back to Earth, scientists discovered that its primary mirror had been manufactured with a tiny but significant error. The mirror's shape was slightly incorrect, causing images to appear blurrier than expected.

For a telescope that had taken years to build and cost a huge amount of money, this was a serious problem.

Fortunately, Hubble had been designed so astronauts could service it in orbit.

In 1993, astronauts travelled to Hubble aboard the Space Shuttle Endeavour and installed corrective equipment and upgraded instruments. The repair worked brilliantly. Suddenly, Hubble began producing the incredibly detailed images scientists had originally hoped for.

Several servicing missions followed over the years, replacing instruments, repairing components and extending the telescope's scientific life.

Looking Deep Into the Universe

One of Hubble's greatest strengths is its ability to observe extremely distant objects.

When we look far into space, we are also looking backward in time. Light from a galaxy millions or billions of light-years away has taken millions or billions of years to reach us. We therefore see that galaxy as it existed long ago.

This idea became especially powerful with observations such as the Hubble Deep Field.

Astronomers pointed Hubble toward what appeared to be a nearly empty patch of sky and allowed the telescope to collect light over many observations. The resulting image revealed thousands of galaxies.

What looked like an empty region of space was actually filled with galaxies stretching far back into cosmic history.

Later deep-field observations pushed this idea even further, helping astronomers study how galaxies formed and changed during the early universe.

Changing Our Understanding of the Cosmos

Hubble has contributed to an extraordinary range of discoveries.

Its observations helped astronomers improve measurements of the expansion rate of the universe. It also played an important role in research involving distant exploding stars and the discovery that the expansion of the universe is accelerating — evidence that led scientists to investigate the mysterious phenomenon we now call dark energy.

Hubble has also helped scientists study supermassive black holes at the centres of galaxies, observe the birth and death of stars, examine planets within our Solar System and investigate planets orbiting other stars.

Astronomers have even used Hubble to study the atmospheres of some exoplanets by examining how starlight changes as a planet passes in front of its star.

Each of these observations adds another piece to the enormous puzzle of how the universe works.

The Images That Inspired Millions

Scientific discoveries are only part of Hubble's legacy.

Images such as the Pillars of Creation became cultural icons. The towering structures of gas and dust inside the Eagle Nebula showed regions where new stars are forming, turning a distant astronomical object into something people around the world could immediately appreciate.

Hubble photographs often use multiple observations and wavelengths of light combined into carefully processed images. The result allows scientists to highlight important structures while also giving the public a spectacular visual window into space.

For many people, these images were their first real introduction to astronomy.

Hubble and the Next Generation of Telescopes

Modern observatories such as the James Webb Space Telescope do not simply make Hubble irrelevant. Different telescopes are designed to study different parts of the electromagnetic spectrum and answer different scientific questions.

Hubble is especially valuable for observations in visible and ultraviolet light, while Webb is primarily designed to observe the universe in infrared wavelengths.

When observations from multiple telescopes are combined, astronomers can build a much richer picture of the same cosmic objects.

More Than a Telescope

Perhaps Hubble's greatest achievement is not a single discovery or photograph.

It changed humanity's perspective.

It showed us that seemingly empty patches of sky contain thousands of galaxies. It allowed us to watch stars being born, examine galaxies from the distant past and explore worlds far beyond our Solar System.

Every Hubble image reminds us of something both humbling and exciting: our planet occupies an incredibly small place in an unimaginably large universe, yet we have developed the ability to look across that universe and begin understanding it.

That is what makes the Hubble Space Telescope more than an orbiting scientific instrument. It is one of humanity's greatest windows into the cosmos.