NASA’s Hubble Telescope has shared a stunning image of a portion of a large galaxy census known as the Great Observatories Origins Deep Survey (Goods). It shows a number of galaxies, denoted by sparkling dots scattered on a dark canvas as if a handful of grains are sprinkled on a dark background. The Twitter post wants to talk about how big our universe is. But determining that could be difficult. For any success, we need to first find out how many galaxies are there in the universe. This question has long perplexed scientists. Thanks to the Hubble Deep Field in the mid-1990s, they were able to get the first real insight into the galaxy population.
Subsequent observations such as Hubble’s “Ultra Deep Field” revealed a myriad of faint galaxies and led to an estimate that the observable universe had about 200 billion galaxies. But scientists in 2016 found out that the universe is a lot more crowded. They came to the conclusion that there are at least 10 times more galaxies in the universe than previously thought.
Let’s talk about how huge our universe is. ????
The Hubble Ultra Deep Field led to an estimate that the observable universe contained at least 200 billion galaxies. But research from 2016 suggests that number is at least 10 times too low: https://t.co/FKh3WTJlKU#DeepFieldWeek pic.twitter.com/MrxIcaYzya
— Hubble (@NASAHubble) August 3, 2021
NASA shared the social media post as part of the ‘Deep Field Week”’, a social media event during which images captured by the Hubble Space Telescope are being shared to recall the early studies of the universe and how they evolved through time. Deep field images help us understand the formation and evolution of galaxies.
Mark your calendars! ✏️
Hubble’s #DeepFieldWeek is happening August 2-6.
Follow along on social media as we take a deep dive into some of Hubble’s most iconic images and what they’ve taught us about our universe – and ourselves.
— Hubble (@NASAHubble) July 30, 2021
Coming back to the 2016 study, astronomers also found that the galaxies were not evenly distributed throughout the universe’s history, meaning a significant galaxy evolution dramatically reduced the number of galaxies through mergers between them.
The decreasing number of stars also solved another question that had confused scientists until then – the Olbers’ paradox, relating to the problem of why is the sky dark at night if the luminous stars are distributed evenly throughout an infinite universe.
The scientists involved in the study concluded that the starlight from the galaxies is invisible to the human eyes because of the expansion of space, the universe’s dynamic nature, and the absorption of light by intergalactic dust and gas.