The Hubble Space Telescope (HST) is undoubtedly one of the most iconic instruments in the history of astronomy. Since its launch in 1990, it has transformed our understanding of the cosmos and made it possible to capture spectacular images that have fascinated scientists and the general public alike.
In this article, we'll explain how Hubble revolutionized astrophotography and modern astronomy.

History of the Hubble Telescope

The idea of a space telescope arose long before technology allowed its construction.

The reasoning behind this idea is that placing a telescope beyond the Earth's atmosphere eliminates the effects of atmospheric turbulence, which distorts observations.

In addition, the atmosphere significantly absorbs electromagnetic radiation at specific wavelengths, especially in the infrared, decreasing the quality and quantity of images that can be obtained.

Ground-based telescopes face challenges such as weather conditions, particularly cloud cover, and light pollution from large urban areas, which limit suitable locations for their placement.

In 1923, German scientist Hermann Oberth first proposed the idea of placing a telescope beyond Earth's atmosphere. The concept gained traction in the 1940s when astronomer Lyman Spitzer emphasized its benefits, stating that a space-based telescope could offer "a clearer and sharper view of the universe, free from the distortions caused by the Earth's atmosphere."

Development of Hubble officially began in the 1970s under the direction of NASA and the European Space Agency (ESA). Named after astronomer Edwin Hubble, who proved that the universe is expanding, the telescope was designed to observe the cosmos without the distortions caused by Earth's atmosphere.
Finally, on April 24, 1990, Hubble was launched into space aboard the space shuttle Discovery and placed in a low-Earth orbit at about 547 kilometers. Although it faced teething problems with its primary mirror, a service mission in 1993 corrected the flaw and marked the beginning of extraordinary contribution to science.

How does the Hubble Telescope work?

The Hubble Space Telescope is an optical observatory that operates outside the Earth's atmosphere. Its main advantage lies in its location: being in space, it avoids distortions caused by the atmosphere, such as turbulence and absorption of specific wavelengths, which make it difficult to observe from Earth.

This gives it an advantage that no other telescope on Earth had at the time, helping to capture otherwise impossible images.

Hubble observes in a range of wavelengths, including visible, ultraviolet, and near-infrared light. This ability makes it highly versatile and allows it to study astronomical phenomena, from star formation to distant galaxies.

Infrared observation is critical because it allows us to peer through clouds of interstellar dust and detect very cold or extremely distant objects. From Earth, these wavelengths are primarily blocked by the atmosphere, making a space telescope like Hubble essential.

Instruments on board Hubble

During servicing missions, Hubble replaced or upgraded several science instruments. Each plays a crucial role in data capture and analysis. Below, we will briefly mention each of them, their function, and their importance.

1. Wide Field Camera 3 (WFC3)

• Function: Takes high-resolution images in visible, ultraviolet and infrared light.
• Significance: It is Hubble's most widely used instrument and has produced many of its iconic images.

2. Advanced Camera for Surveys (ACS)

• Function: Captures detailed images of large regions of the sky.
• Importance: Ideal for the study of distant galaxies and galaxy clusters.

3. Cosmic Origins Spectrograph (COS)

• Function: It studies the composition and structure of the universe through ultraviolet spectra.
• Significance: It has provided insights into galaxy evolution and dark matter.

4. Space Telescope Imaging Spectrograph (STIS)

• Function: Combines images and spectra to study planetary atmospheres and black holes.
• Significance: Crucial for investigating exoplanets and accretion disks around black holes.

5. Fine Guidance Sensors (FGS)

• Function: Ensure the telescope's stability by pointing precisely at targets.
• Importance: They allow accurate and constant observations.

The astrophotography revolution

Since it was put into operation, Hubble has completely changed the way in which the universe is observed. Now, without an atmosphere that came between the objects and the telescope, the images obtained were 100% free of any aberration, and with the huge primary mirror of 2.4 meters, it could capture very sharp images of distant objects.

However, Hubble's most significant contribution was not the photographs but the discoveries made thanks to those images, which have redefined our understanding of the universe.

Thanks to the images provided by Hubble, more than 19,000 scientific articles have been published, consolidating it as one of the most prolific instruments in the history of modern astronomy.

Although it is impossible to mention in this article all the discoveries that have been made thanks to the Hubble telescope, we can mention at least 5 of the most outstanding:

1. Hubble Deep Field Image

In 1995, astronomers used Hubble to capture the Deep Field image, pointing at a seemingly empty region of the sky for 10 days.

This experiment revealed about 3,000 galaxies, some so distant that the light we see from them began its journey more than 13 billion years ago, near the universe's beginning.

The image showed galaxies at different stages of evolution, providing an unprecedented glimpse into how they grew and developed. This finding changed the perception of the cosmos by demonstrating that even in the darkest areas of the sky, the universe is teeming with galaxies.

The Hubble Deep Field continues to be a reference for cosmological studies, helping to determine the density and distribution of galaxies in the early universe and feeding theoretical models on the formation of cosmic structures.

2. Discovery of exoplanets and planetary atmospheres

Although Hubble was not explicitly designed to study exoplanets, it has significantly contributed to this emerging field. Using techniques such as transit spectroscopy, astronomers have analyzed the atmospheres of exoplanets by observing how light from their stars passes through their gaseous layers, a method known as "transit."

In 2001, Hubble first detected an exoplanet's atmosphere, HD 209458 b, finding evidence of sodium. Since then, it has identified molecules such as water, carbon dioxide, and methane in planetary atmospheres, providing clues to their habitability.

This work has been crucial in preparing the ground for more advanced research, such as that carried out by the James Webb Telescope. Hubble's observations have greatly expanded our knowledge about the diversity of planets outside the Solar System and the conditions necessary for life.

3. Accurate measurements of the expansion rate of the universe

Hubble has played a crucial role in measuring the expansion rate of the universe, known as the Hubble constant. By observing type 1a supernovae, which are standard distance markers, and combining this data with those from galaxy clusters, the telescope accurately measured this constant.

In the 1990s, Hubble confirmed that the universe was expanding and doing so at an accelerating rate, a revolutionary discovery that led to the idea of dark energy. This mysterious component makes up approximately 68% of the universe and remains one of the greatest enigmas in cosmology.

Hubble's measurements have refined our understanding of the scale of the cosmos and how it has evolved since the Big Bang, laying the groundwork for future research into the nature of dark energy.

4. Study of supermassive black holes

Hubble has provided conclusive evidence that most galaxies host supermassive black holes at their centers.

Using spectroscopic observations, the telescope detected motions of stars and gas at extreme speeds around these compact objects, confirming their existence.

For example, in the galaxy M87, Hubble measured the rotation of the gas disk near the core, revealing a black hole with a mass billions of times that of the Sun.

These discoveries have helped scientists understand the relationship between black holes and galactic evolution, including the influence of these giants on star formation and the distribution of matter.

In addition, Hubble data have been instrumental in identifying how black holes interact with their environment, shedding light on the most extreme processes in the universe.

5. The sharpest images of galaxies and nebulae

The images captured by Hubble have redefined the way we observe the universe. The "Pillars of Creation" in the Eagle Nebula are an iconic example.

These structures are giant plumes of gas and dust where stars are born, and images taken by Hubble have revealed intricate details of these processes. Like other galaxies, such as Andromeda, the telescope captured stunning views, allowing astronomers to map their structures, including star clusters and star-forming regions.

In addition, Hubble images have provided visual evidence of colliding galaxies, showing how these interactions shape the structure of the cosmos.

Not only do these photographs have immense scientific value, but they have also popularized astronomy, bringing the cosmos closer to the general public than ever before.

Hubble today

Today, the Hubble Space Telescope remains a vital tool for astronomy, working with more modern telescopes such as the James Webb Space Telescope (JWST).

While Hubble specializes in observations in ultraviolet and visible light, its infrared capabilities complement Webb's, providing a more complete view of the cosmos.

Its current role includes studying nearby galaxies, stellar evolution, and transient phenomena, such as supernovae. Although it has operated for over 30 years, Hubble continues to make important discoveries and help refine our cosmological theories.

Hubble's legacy

The Hubble Space Telescope has been one of humanity's most significant scientific and technological achievements. Thanks to it, we have obtained answers to fundamental questions about the universe and opened new questions for the future.

Without Hubble, our understanding of the cosmos would be limited. From the confirmation of the existence of dark energy to the first detailed images of distant galaxies and the discovery of exoplanets, its impact on astronomy and popular culture is incalculable.

Hubble has not only shown us the universe as we've never seen it before but has also inspired generations of scientists and dreamers. Hubble Space Telescope's legacy will continue to shine as a beacon of knowledge and exploration. as we move into new frontiers with James Webb and other telescopes.