How dark is a place? Global glue displays There are fewer galaxies than we thought, scientists say

The cosmos just became a darker and more lonely place.

NASA’s New Horizons spacecraft outside Pluto has taken a modern measure of the Earth’s background – with amazing results. It turns out that there are far fewer galaxies out there than previously thought.

Here’s everything you need to know about the call of the Universe – and what it reveals.

Why measure the cry of the Earth?

Measuring the sexual darkness of the night sky allows astronomers to estimate the number of galaxies in the Universe, both visible and unseen. “It’s an important number – how many galaxies are there?” said Marc Postman of the Space Telescope Science Institute in Baltimore, Maryland, lead author of a study presented yesterday at the January 2021 meeting of the 237th American Astronomical Society.

As it turned out there are far fewer galaxies than astronauts say.

What is a ‘microwave cosmic background’?

The radiation left over from the Big Bang – a weak background – is called the cosmic microwave (CMB) background. Glow’s famous but rather light glow – long-wave microwave radiation since there were stars – it fills the Universe, and is strong evidence for Big Bang theory.

It is much closer to the origin of the Earth than stars and galaxies.However, it is the CMB No do not research this study.

What is an optical cosmic background? ‘

It is a light made by stars and supernovae – the absolute cry of all galaxies – in the entire history of the Earth, so it is a cosmological criterion.

The cosmic optical background (COB) is essentially identical to the visible of the CMB.

“While microwave cosmic background tells us about the first 450,000 years after the Big Bang, the optical cosmic background tells us something about the total number of stars ever created. since then, ”said Postman. “It limits the total number of galleries that have been created, and where they could be in time. ”

What is the ‘New Horizons’ spaceship?

After leaving Earth in 2006 to become the fastest moving spacecraft for humanity, NASA’s New Horizons probe visited Pluto in 2015 and Arrokoth in 2019. It is now 50 astronauts from Earth. – more than 4 billion miles / 7 billion kilometers from Earth – in a disk around the far-flung Solar System called the Kuiper Belt.

The scientists used the Long Range Reconnaissance Imager (LORRI) at the spacecraft, an 8-inch / 20 centimeter telescope. “These kinds of measurements are very difficult. Many people have tried to do this for a long time, ”said Tod Lauer, a scientist at the NSF’s NOIRLab, another lead author in the study. “New Horizons gave us space to measure optical cosmic background better than anyone could. ”

What’s wrong with the Hubble Space Telescope?

Using LORRI data from outside Arrokoth, scientists were able to use a sky about 10 times darker than the darkest sky accessible to the Hubble Space Telescope, which orbits the Land.

Simply put, the Earth’s atmosphere and sunlight in the Solar System make it useless for a sensitive measurement of the COB. The darkness of the Outdoor Solar System enabled the scientists to separate the COB from the removal of scattered light from bright stars and galaxies, narrow stars, zodiacal light and diffused light from the Milky Way.

What is zodiacal light? ‘

It is “light pollution” in the Solar System. Literally meaning light from the “circle of animals” – the zodiac constella of the Earth’s ecliptic – the zodiacal light is also referred to as “false morning” and “false twilight”. ”

Reflective sunlight from a cloud of interplanetary dust around the Sun, zodiacal light is like dust from passing comets in the asteroid belt (between Mars and Jupiter orbits) and the Kuiper Belt (in the Neptune’s orbital solar system.

Zodiacal light radiates across the optical spectrum down to long-wavelength infrared.

It is visible from Earth – albeit only in very dark sky destinations – as a cone of light that looks something like an “V.” upside down or far away.

The farther you get from the equator, the lower it is on the horizon and the more it can see.

For this test the zodiacal light must be avoided.

So clear is the Universe?

“The universe is dark, but it’s not as dark as we thought,” Lauer said. After measuring the Earth’s cry, Lauer and his colleagues removed known sources such as the stars in the Milky Way and reflections from interstellar dust only to discover that some light was not accounted for. .

So what is the source? Options include:

• A rugged galaxan in the nearby Universe has not yet been discovered.
• The scattered halos of stars surrounding galaxies may be brighter than expected.
• Many rocky, intergalactic stars are scattered throughout the cosmos.
• Many galaxies are farther away than theories suggest.

However, perhaps the most surprising finding is that the Earth’s background is too weak to support conventional theories of how many unseen galaxies there are.

It was previously estimated by the Hubble Space Telescope that there were two trillion + galaxies out there, mostly beyond sight, but these new figures suggest that it may be just hundreds of billions.

“Take all the galleries that Hubble sees, double that number, and that’s what we see – but there’s nothing more,” said Lauer.

Wishing you clear skies and wide eyes.