Homage to the Time Travelers of the Universe
The new Space Telescopes are helping us learn about our Universe
Introduction
In this post, I present a brief history of the latest Space Telescopes, some aspects of our Universe, and how images are created for our viewing. I also present four images each, from the three international telescopes: the Hubble, James Webb, and Euclid, respectively. I encourage you to visit each website (see the References at the end of this post) to view the many spectacular images of the Universe.
I would like to thank the men and women – physicists, astronomers, cosmologists, engineers, and support staff – who have created, operated, and maintained the latest generation of Space Telescopes that peer into the farthest reaches of time and space. These men and women have devoted their lives and careers to advancing our knowledge of the Universe.
A Brief History of the Space Telescopes
The Hubble telescope, which orbits the Earth, was launched from the Space Shuttle Discovery on April 24, 1990. It has been sending images back to Earth for over thirty years. In 2009, there was a successful mission involving astronaut space walks to integrate new instruments, repair broken equipment, and replace critical components on the Hubble.
The James Webb telescope went into space on December 21, 2021. It does not orbit the Earth like the Hubble; instead, it orbits the Sun at one million miles from Earth. The James Webb telescope is very complex but has performed flawlessly.
The newest member of the Space Telescope family is Euclid. It was developed by the European Space Agency (ESA) and the Euclid Consortium and launched on July 1, 2023.
According to the ESA website, it also sits in orbit around the Sun at one million miles from Earth.
According to Wikipedia, Euclid has a 600-megapixel camera – in comparison, my Leica digital camera has a 47-megapixel sensor – records visible light, a near-infrared spectrometer, and photometer to determine the redshift of detected galaxies.
According to the ESA website:
Euclid is named after the Greek mathematician Euclid of Alexandria, who lived around 300 BC and founded the subject of geometry. As the density of matter and energy is linked to the geometry of the universe, the mission was named in his honour.
The Euclid mission is very ambitious: to explore the evolution of the Dark Universe. With time as the third dimension, it will make a 3D Universe map. It will observe billions of galaxies as far back as 10 billion light-years.
What is a light year?
One light year is the distance an object, traveling at the speed of light – 186,000 miles per second or 671 million miles per hour – can travel in one Earth year. For example, light from our Sun, about 92 million miles from Earth, takes 8 minutes to reach us.
How does time become the third dimension of the 3D Universe map?
Consider snapshots of space – a portion of space measured in length and width – taken at different points in time: now, one light-year ago,100 light-years ago, up to 10 billion light-years ago. These snapshots will differ as we go back in time, as we get closer to the beginning of our Universe. Euclid’s images of space will be used to construct the 3D map.
What is the Dark Universe?
The Dark Universe examines the invisible dark matter underlying galaxies. Together with dark energy, the two constitute 95 percent of the Universe’s total energy and mass. Dark Matter tends to keep the Universe together, while Dark Energy tends to drive it apart. I refer you to NASA’s Chandra page for details.
How do they create the images we see?
These telescopes have instruments with sensors – similar to those in our digital cameras – that take images in the infrared and ultraviolet portions of the electromagnetic spectrum; these are not visible to the human eye. This chart of the electromagnetic spectrum shows where the Hubble and James Webb Telescopes operate. The Euclid telescope operates in the visible and near-infrared spectrum. The Spitzer Space Telescope was retired by NASA in 2020.
Since the human eye cannot see infrared images, telescopes use advanced filters to detect specific elements or molecules. The final image is a layered composite of distinct images taken with different filters.
Here is an example of the Pillars of Creation, seen through separate filters and the composite on the right.
Next, the imaging specialists carefully assign individual images from Webb’s various filters to blue, green, and red channels to align with the colors the human eye perceives.
Color is applied chromatically: The shortest wavelengths are assigned blue, slightly longer wavelengths are assigned green, and the longest wavelengths are assigned red. If more than three images make up the final composite image, purple, teal, and orange may be assigned to additional filters that fall before or in between blue, green, and red. Assembling the color image from these images gives our imaging specialists the initial composite image. Yes, there is still work to be done! These initial color images are still only drafts.
The final images go through a process similar to what we photographers do in Lightroom. The white balance is determined by pointing to a star's core, and using it to equalize the white across the image.
Here is the sequence of edits with the final one on the right.
Here is the final version of the Pillars of Creation as taken from the James Webb site:
Spectacular Images from the Three Telescopes
Before we begin, let’s define the terms Nebula and Galaxy.
According to NASA, “[a] nebula is a giant cloud of dust and gas in space. Some nebulae (more than one nebula) come from the gas and dust thrown out by the explosion of a dying star, such as a supernova. Other nebulae are regions where new stars are beginning to form. For this reason, some nebulae are called "star nurseries." (https://spaceplace.nasa.gov/nebula/en/)
On the other hand, a galaxy is a huge collection of gas, dust, and billions of stars and their solar systems. A galaxy is held together by gravity. Our galaxy, the Milky Way, also has a supermassive black hole in the middle” (https://spaceplace.nasa.gov/galaxy/en/)
Below are images from the three space telescopes discussed above.
Hubble Telescope Images
James Webb Telescope Images
Euclid Telescope
In conclusion, the images from these telescopes have been highly processed for maximum impact. The infrared images have been converted to images the human eye can see. With each new telescope, we gain new insights and knowledge into the nature of our Universe.
Acknowledgments
I would like to thank Ronnie Beth Sauers and Ben Kerschberg, who writes at Hefty Matters, for the insights and edits that have improved the presentation of this challenging subject.
References
The Hubble Space Telescope, https://hubblesite.org
The James Webb Telescope. https://webbtelescope.org/news/first-images/gallery
The Euclid Space Telescope: https://www.esa.int/Science_Exploration/Space_Science/Euclid_overview
The Chandra X-Ray Observatory: https://chandra.harvard.edu/index.html
Thank you for the beautiful images and the simple yet thorough explanation of these telescopes.
I knew so little of the intricacies of these telescopes... thank you for this extraordinarily informative and interesting read.