How Hubble opened our eyes to the universe’s first galaxies – Astronomy Magazine

Astronomers have the privilege of watching things happen in the past which they call the lookback time. Our best measurement of the age of the universe is 13.7 billion years. The distance that light travels in one year is called a light year. The most distant galaxies observed by NICMOS were at a distance of almost 13 billion light years. This meant that the light that NICMOS detected had been traveling for 13 billion years and showed what the galaxies looked like 13 billion years ago, a time when the universe was only about 5% of its current age. These were some of the first galaxies ever created and were forming new stars at rates that were more than a thousand times the rate at which most galaxies form stars in the current universe.

Although astronomers have studied star formation for decades, many questions remain. Part of the problem is that most stars are formed in clouds of molecules and dust. The dust absorbs the ultraviolet and most of the optical light emitted by forming stars, making it difficult for Hubbles ultraviolet and optical instruments to study the process.

The longer, or redder, the wavelength of the light, the less is absorbed. That is why sunsets, where the light must pass through long lengths of dusty air, appear red.

The near infrared, however, has an even easier time passing through dust than the red optical light. NICMOS can look into star formation regions with the superior image quality of Hubble to determine the details of where the star formation occurs. A good example is the iconic Hubble image of the Eagle Nebula, also known as the pillars of creation.

The optical image shows majestic pillars which appear to show star formation over a large volume of space. The NICMOS image, however, shows a different picture. In the NICMOS image, most of the pillars are transparent with no star formation. Stars are only being formed at the tip of the pillars. The optical pillars are just empty dust reflecting the light of a group of nearby stars.

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How Hubble opened our eyes to the universe's first galaxies - Astronomy Magazine