Hubble Space Telescope: History, Facts & Discoveries

Instructor: Jeff Fennell

Jeff has a master's in engineering and has taught Earth science both domestically and internationally.

The Hubble Space Telescope was launched into orbit in 1990 to observe stellar objects. It has gathered spectacular images and helped advance knowledge in all aspects of cosmology. This lesson will cover information about the Hubble Space Telescope.


The Hubble Space Telescope (HST) is a visual telescope in Earth's orbit. It was first conceived in the 1920s, but it would take another 70 years for it to be launched. The Hubble Space Telescope is a U.S. National Aeronautics and Space Administration (NASA) and European Space Agency (ESA) joint project, the main goal of which is to establish a long-term observatory in space. It is named after the American astronomer Edwin Hubble whose work in cosmology led to the modern understanding of the universe.

On April 25, 1990, the Hubble telescope was launched into orbit on the back of the U.S. space shuttle. Costing nearly $3 billion to design and construct, the Hubble weighs 11.6 tons and is 13.3 meters in length with a diameter of 4.3 meters. It travels at 28,000 kilometers per hour in orbit.

Hubble Space Telescope

One of the major advantages of the Hubble is that there is no atmospheric interference in space. Its images are highly stable and clarity is up to ten times greater than that of ground telescopes. The Hubble Space Telescope helps scientists study the universe and gain a deeper understanding of stellar objects. The HST consists of instruments that observe in the near ultraviolet, visible, and near infrared wavelengths. For power, it includes two solar panels, 11.8 meters long and 2.3 meters wide, that provide 2.4 kilowatts of solar power.

In April 1990, a few weeks after the Hubble Space Telescope was launched, the researchers found that there was a serious problem from the images returned by the Hubble Space Telescope. Through analyzing the pattern defect, they were able to determine that the problem came from the shape of the primary mirror, which was built wrong. Although this difference was less than 1/20 of a light wavelength, the difference caused the images to be highly distorted. In 1993, repairs were carried out on the Hubble Space Telescope to correct the mirror. Since then, HST has outperformed everyone's expectations.

Eagle Nebula photographed by HST

Crab Nebula photographed by HST


Age of the Universe

The Hubble Space Telescope can determine the Hubble constant by measuring the distance to Cepheids (a class of variable stars about which the luminosity and pulsation period are known, which can, therefore, be used as standard candles for establishing distance outside of the galaxy). Hubble's observations of Cepheid distances dropped uncertainty to around 10%, giving the expansion rate and age of the universe more precise values.

Star Formation

The Hubble Space Telescope also helped researchers discover nebula star-forming regions, such as in the Orion nebula. Although theoretical calculations and indirect observations implied the existence of these disks, the high-resolution Hubble revealed the first images of these structures and helped researchers understand the physical properties of the disk.

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