Have you ever wondered what our universe was like in its earliest stages? For all the curious, the Hopkins-run Hubble Space Telescope has just discovered one of the youngest and brightest galaxies in our universe.
The study, which appears in an upcoming issue of the journal Astrophysical Journal, promises to reveal crucial information about how our universe developed in the so-called dark ages.
Astronomers from several universities, including Hopkins, used the Hubble telescope to find the galaxy, called A1689-zD1.
The dark ages refer to the first few million years after the Big Bang, when the universe had started to cool but there was still very little organized matter. Galaxies like the one observed contributed significantly to the universe's development.
When you look up at the night sky, you are really looking back in time. Since the speed of light is finite, the light you are seeing today might have been emitted centuries or millennia before. For example, it takes sunlight three minutes to reach Earth, so the sun has been up for three minutes already when it appears on the horizon in the morning.
The Hubble telescope, one of the most powerful telescopes ever built, has peeked back farther in time than almost any other device.
What is special about this particular galaxy is that astronomers had never before observed such a well-organized object so far back in time. It was surprising to find a newborn galaxy only about 700 million years after the universe began. Scientists estimate the universe is about 13.7 billion years old.
In this way, astronomers are capable of writing a type of history book of the universe by discovering objects that are farther and farther away - in distance and in time.
To detect this galaxy, astronomers had to use special imagers on Hubble because the galaxy is invisible to the naked eye due to an effect known as red shift.
Since our universe is expanding, every object - stars, galaxies - is moving away from us. This motion has an influence on the light that is emitted by them: the waves are being stretched out by the outward motion, which causes their wavelength to increase. An increase in wavelength causes all of the light emitted by that object to become more red or infrared from the perspective of viewers on Earth.
A second trick was needed to see this object: gravitational lensing. Nearby star clusters are used to magnify the light of the object. According to Einstein's laws, heavy objects in space attract everything, including light. So the actual path of light is bent and travels on a curve around a massive object such as a star cluster. Following this logic, the telescope does not look right at the galaxy but rather a little to the side to see a ray of light.
Despite these efforts to hunt for every bit of light, all Hubble can see are knots and blurry images, which still reveal a lot compared to the detail of other objects so far back in time.
The researchers are currently following up the Hubble observation with the Keck telescope on Mauna Kea, Hawaii. This is an important part of the study since they need one more source of information to confirm the distance of the galaxy.
As of now, the scientists are eager to observe the same galaxy with Hubble's planned successor, the James Webb Space Telescope, whose primary mirror will be seven times as large when it launches in 2013. Its partner on Earth will be the ALMA radio telescope, which will be completed in 2012.
