Happy birthday, Hubble!

Monday, April 26, 2010
by Nikki Staab

Hubble image

For 20 years, people around the world have enjoyed the beauty and brilliance of the heavens thanks to the Hubble Space Telescope (HST), the world’s first space-based optical telescope. April 24 was the 20th anniversary of Hubble’s launch. 

ASU astronomer Rogier Windhorst has been involved with more than 45 Hubble projects. Working with the telescope’s images, he has helped us understand the structure of the universe and how distant galaxies form and evolve. Currently, he is working to image nearby and distant galaxies using the new camera that the space shuttle astronauts installed in Hubble in May 2009. Here he answers some questions about Hubble's operation and the discoveries it sparked.

Q: What’s the long-term importance of Hubble?
A: Hubble has been arguably the most profound and productive telescope and science instrument launched since Galileo first looked at the skies through a telescope in the early 1600s. Despite the initial issues with Hubble’s mirrors, which were fixed by astronauts in December 1993, Hubble has exceeded all expectations, and then some. It has truly revolutionized astronomy. You can hardly find a school or university in the nation that does not have some spectacular Hubble images posted somewhere.

Q: What are the top three things you’ve learned because of Hubble?
A: First, we now know how fast the universe is expanding thanks to Hubble. Related to this, we now know the age of the universe to be 13.67 billion years.

Second, we have learned the way galaxies form and evolve over cosmic time, and how supermassive black holes grow in their centers. Both are a major piece of the puzzle of how stars and galaxies formed throughout cosmic time.

And, third, we’ve learned how young stars in dwarf galaxies likely finished the so-called epoch of Cosmic Reionization. This was the last major phase transition in the universe. Hubble showed that this process was completed about a billion years after the Big Bang, when almost all remaining hydrogen gas in the universe was split into its individual protons and electrons by the intense ultraviolet light from hot stars in these young galaxies. This event turned the universe from opaque to transparent, and enabled Hubble to look back into cosmic history to when the universe was eight to nine times smaller than today, and only about 700 million years old.

Q: What are your favorite Hubble images?
A: I have three: they all were made at ASU.

First, the Eagle Nebula:

Eagle Nebula

Second, the Dawn of Galaxies from the Hubble Ultra Deep Field: 

Dawn of galaxies

Third, the new very colorful Hubble Wide Field Camera 3 images:

Hubble Wide Field image

Q: What is the biggest change in science from before to after Hubble?

A: We had no idea that faint and distant galaxies were so numerous and small. They are full of active regions of star-formation, where the heavy elements were made throughout cosmic time. Hubble has revealed to us in detail most of this epoch of galaxy assembly and supermassive black hole growth.

Before Hubble, galaxy evolution was thought of as a neat, slow and steady process, like cars moving slowly off a factory assembly line. After Hubble, we know this process is actually chaotic, random, and sometimes very sudden, full of spectacular galaxy collisions, like watching the Indy 500 or the Daytona 500. Hubble has shown us that life in the cosmic fast lane never gets boring.

Q: Did you ever imagine Hubble would last 20 years?
A: Not initially, but then after I saw NASA successfully pull off the first shuttle servicing mission to Hubble in December 1993, I thought, well, this dream may stay alive forever, or at least go on for the length of a human career. It has been truly life-changing, with never one boring day. It’s like being thirsty in the desert and being able to sip from a fire hydrant.


Windhorst has been involved in upgrades to the Hubble, as well as the development of its successor, the James Webb Space Telescope (JWST). JWST is scheduled to be launched in 2014.

Hubble images from the last 20 years are online at: http://www.stsci.edu/outreach http://hubblesite.org/newscenter/archive

Image files and additional information about the Hubble Space Telescope are at: http://hubblesite.org http://www.stsci.edu/resources http://www.nasa.gov/mission_pages/hubble/main/index.html