A New Test Confirms Dark Energy and the Expansion of the Universe

A map of galaxy clustering in the universe. Credit: Seshadri Nadathur

In the standard model of cosmology, dark energy fills the universe. It causes the universe to expand at an ever-increasing rate, and it makes up more than 70% of the cosmos. But there’s a problem. When we measure the rate of cosmic expansion in different ways, we get results that disagree with each other.

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Study of 200,000 Galaxies Reveals the Entire Universe Might Have Been Spinning in One Direction Early On

Some of the most dramatic events in the Universe occur when certain stars die — and explode catastrophically in the process. Such explosions, known as supernovae, mainly occur in a couple of ways: either a massive star depletes its fuel at the end of its life, become dynamically unstable and unable to support its bulk, collapses inwards, and then violently explodes; or a white dwarf in an orbiting stellar couple syphons more mass off its companion than it is able to support, igniting runaway nuclear fusion in its core and beginning the supernova process. Both types result in an intensely bright object in the sky that can rival the light of a whole galaxy. In the last 20 years the galaxy NGC 5468, visible in this image, has hosted a number of observed supernovae of both the aforementioned types: SN 1999cp, SN 2002cr, SN2002ed, SN2005P, and SN2018dfg. Despite being just over 130 million light-years away, the orientation of the galaxy with respect to us makes it easier to spot these new ‘stars’ as they appear; we see NGC 5468 face on, meaning we can see the galaxy’s loose, open spiral pattern in beautiful detail in images such as this one from the NASA/ESA Hubble Space Telescope.

Almost everything in the universe spins. Planets rotate on their axis, stars spin around black holes, and galaxies spin in great spiral structures. But what about the universe as a whole?

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Powerful Telescope Confirms There’s an Earth-Sized World Orbiting Proxima Centauri

Artist view of the surface of Proxima Centauri b. Credit: ESO/M. Kornmesser

The closest star to the Sun is a small red dwarf star known as Proxima Centauri. It is only 4.2 light-years away and is now known to have an Earth-sized planet in its habitable zone. That doesn’t mean there is life orbiting the nearest star, but its proximity should help us understand the possibilities.

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Maybe a Fleet of Tiny Spacecraft Could Help Detect a Primordial Black Hole Planet 9

The possible orbit of Planet Nine. Credit: CalTech/R. Hurt (IPAC)

There are eight classical planets in our solar system, from speedy Mercury to distant Neptune. There are also numerous dwarf planets, such as Pluto and Ceres. While we continue to find more dwarf planets, there are some hints that another large planet could lurk far beyond Neptune. This Planet Nine is thought to be a “super-Earth” about five times the mass of our planet, which would make it about twice as large as Earth. But despite several searches for the planet, it has not yet been found.

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Hundreds of New Gravitational Lenses Discovered to Help Study the Distant Universe

These two columns show side-by-side comparisons of gravitational lens candidates imaged by the ground-based Dark Energy Camera Legacy Survey (color) and the Hubble Space Telescope (black and white). (Credit: Dark Energy Camera Legacy Survey, Hubble Space Telescope)
These two columns show side-by-side comparisons of gravitational lens candidates imaged by the ground-based Dark Energy Camera Legacy Survey (color) and the Hubble Space Telescope (black and white). (Credit: Dark Energy Camera Legacy Survey, Hubble Space Telescope)

General relativity tells us that everything, even light, is affected by the mass of an object. When a beam of light passes near a large mass, its path is deflected. This shift in the direction of light is known as gravitational lensing, and it was one of the first confirmed effects of Einstein’s theory.

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The Tunguska Explosion Could Have Been Caused By An Asteroid That Still Orbits The Sun

Impact zone of the 1908 Tunguska Event. Credit: Wikipedia user Denys

On a cool Summer morning in 1908, a fireball appeared over Northern Siberia. Eyewitnesses described a column of blue light that moved across the sky, followed by a tremendous explosion. The explosion leveled trees across more than 2,000 square kilometers. The explosion is consistent with a large meteor strike, but to this day no evidence of a crater has been found. Now known as the Tunguska Event, its cause remains a mystery to this day.

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High Energy Neutrinos Are Coming From Supermassive Black Holes

ANITA being prepared for launch. Credit: NASA Goddard

Neutrinos are mysterious and elusive particles. They have a tiny mass, no electric charge, and they interact with other matter only rarely. They are also extremely common. At any moment, about 100 billion neutrinos are streaming through every square centimeter of your body. Neutrinos were produced by the big bang, and are still being produced by everything from stars to supernovae.

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One Step Closer to Interstellar Travel. A Successful Microgravity Test of a Graphene Light Sail

Artist concept of lightsail craft approaching the potentially habitable exoplanet Proxima b. Credit: PHL @ UPR Arecibo

If we want to travel to the stars, we’re going to have to be creative. Conventional rockets aren’t nearly powerful enough to allow us to journey across light-years in a reasonable time. Even nuclear rockets might not be enough. So what’s humanity to do? The answer could be a light sail.

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A Fast Radio Burst Has Been Detected From Inside The Milky Way

An illustration fast radio bursts in the night sky. Credit: James Josephides/Mike Dalley

Now and then there are bright flashes of radio light in the sky, and they are bothering astronomers. They are called Fast Radio Bursts (FRBs), and they’re like the chirp of a smoke alarm that needs its battery changed. They last for such a short time that it’s difficult to track down the source. They have become a nagging mystery in astronomy.

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The Sun is less active magnetically than other stars

GOES-17 Solar Ultraviolet Imager captures the Sun at different wavelengths. Credit: NOAA

Our Sun is the source of life on Earth. Its calm glow across billions of years has allowed life to evolve and flourish on our world. This does not mean our Sun doesn’t have an active side. We have observed massive solar flares, such as the 1859 Carrington event, which produced northern lights as far south as the Caribbean, and drove electrical currents in telegraph lines. If such a flare occurred in Earth’s direction today, it would devastate our electrical infrastructure. But fortunately for us, the Sun is mostly calm. Unusually calm when compared to other stars.

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