Brian Koberlein, Author at Universe Today

May 7, 2021May 7, 2021 by Brian Koberlein

We Could Detect Extraterrestrial Satellite Megaconstellations Within a few Hundred Light-Years

A map of space debris orbiting Earth. Credit: European Space Agency

Starlink is one of the most ambitious space missions we’ve ever undertaken. The current plan is to put 12,000 communication satellites in low-Earth orbit, with the possibility of another 30,000 later. Just getting them into orbit is a huge engineering challenge, and with so many chunks of metal in orbit, some folks worry it could lead to a cascade of collisions that makes it impossible for satellites to survive. But suppose we solve these problems and Starlink is successful. What’s the next step? What if we take it further, creating a mega-constellation of satellites and space stations? What if an alien civilization has already created such a mega-constellation around their world? Could we see it from Earth?

May 5, 2021May 5, 2021 by Brian Koberlein

Dark Matter Could Change the Temperature of Exoplanets, Allowing us to Detect it

Artist view of a Jupiter-like exoplanet. Credit: NASA/Goddard Space Flight Center/S. Wiessinger

Ah, dark matter, you continue to allude us. The stuff is incredibly difficult to study. It doesn’t interact with light, so our evidence of it is based upon its gravitational effects on light and visible matter. And the biggest difficulty is that we still don’t know what it is. Efforts to detect dark matter directly have come up empty, as have indirect methods such as looking for evidence of dark matter through things such as excess gamma-rays in the Milky Way. But astronomers continue to think up new ways to detect the stuff, such as a recent study published in Physical Review Letters.

May 2, 2021May 2, 2021 by Brian Koberlein

Breakthrough Listen Searched for Signals From Intelligent Civilizations Near the Center of the Milky Way

A view of the Green Bank Telescope. Credit: Jiuguang Wang/CC BY-SA 2.0

The Breakthrough Listen project has made several attempts to find evidence of alien civilizations through radio astronomy. Its latest effort focuses attention on the center of our galaxy.

April 30, 2021April 30, 2021 by Brian Koberlein

11-Sigma Detection of Dark Energy Comes From Measuring Over a Million Extremely Distant Galaxies

Exploration of the Universe by the SDSS mission during the past two decades (1998-2019). Credit: eBOSS collaboration

After galaxies began to form in the early universe, the universe continued to expand. The gravitational attraction between galaxies worked to pull galaxies together into superclusters, while dark energy and its resulting cosmic expansion worked to drive these clusters apart. As a result, the universe is filled with tight clusters of galaxies separated by vast voids of mostly empty space.

April 27, 2021April 27, 2021 by Brian Koberlein

Smallest, Closest Black Hole Ever Discovered is Only 1,500 Light-Years Away

Artist concept of V723 Mon and its companion. Lauren Fanfer/Ohio State

In theory, a black hole is easy to make. Simply take a lump of matter, squeeze it into a sphere with a radius smaller than the Schwarzschild radius, and poof! You have a black hole. In practice, things aren’t so easy. When you squeeze matter, it pushes back, so it takes a star’s worth of weight to squeeze hard enough. Because of this, it’s generally thought that even the smallest black holes must be at least 5 solar masses in size. But a recent study shows the lower bound might be even smaller.

April 25, 2021April 25, 2021 by Brian Koberlein

A new Technique Could use Quasars to Directly Measure the Expansion Rate of the Universe

an artistic concept of a quasar — Concept image of a galactic quasar. Astronomers used the Event Horizon Telescope to study details at the heart of one like this called NRAO 530. Credit: ParallelVision, Pixabay

One of the biggest challenges to measuring the expansion of the universe is the fact that many of the methods we use are model-dependent. The most famous example is the use of distant supernovae, where we compare the standard brightness of a Type Ia supernova with their apparent brightness to find their distance. But knowing the standard brightness depends upon comparing them to the brightness of Cepheid variables which is in turn determined by measuring the distances of nearby stars via parallax. Every step of this cosmic distance ladder depends upon the step before it.

April 20, 2021April 20, 2021 by Brian Koberlein

One Idea to Explain Dark Matter – Ultralight Bosons – Fails the Test

Dr. Kip Thorne made it clear that black is not the primary hue of Black Holes. His guidance offered to Nolan raised science fiction to a new level. Credit: Paramount Pictures/Warner Bros.

Dark matter continues to resist our best efforts to pin it down. While dark matter remains a dominant theory of cosmology, and there is lots of evidence to support a universe filled with cold dark matter, every search for dark matter particles yields nothing. A new study continues that tradition, ruling out a range of dark matter candidates.

April 17, 2021April 17, 2021 by Brian Koberlein

You Thought Black Hole Event Horizons Looked Strange. Check out Binary Black Hole Event Horizons

The lensing effects can be complex and difficult to calculate. Credit: NASA’s Goddard Space Flight Center/Jeremy Schnittman and Brian P. Powell

One of the strangest predictions of general relativity is that gravity can deflect the path of light. The effect was first observed by Arthur Eddington in 1919. While the bending effect of the Sun is small, near a black hole light deflection can be significant. So significant that you need a powerful supercomputer to calculate how light will behave.

April 14, 2021April 14, 2021 by Brian Koberlein

Finding Oxygen on an Alien World Doesn't Always Mean There's Life There

Artist concept of the planetary system Kepler 62. Credit: Danielle Futselaar - SETI Institute

We now know the universe is filled with planets. By one estimate, there are more than 20 billion Earth-like worlds in our galaxy alone. But how many of them are likely to have life? And how would we know if they do? Unless they happen to send us a very clear message directly, the most likely way we’ll discover exoplanet life is by looking at their atmospheres.

April 12, 2021April 12, 2021 by Brian Koberlein

Brown Dwarfs can Spin so Fast They Almost Tear Themselves Apart

Comparing the rotation of a brown dwarf with Jupiter and Saturn. Credit: Robert Hurt (IPAC/Caltech)

We tend to image planets as spheres. Held together by gravity, the material of a planet compresses and shifts until gravity and pressure reach a balance point known as hydrostatic equilibrium. Hydrostatic equilibrium is one of the defining characteristics of a planet. If a planet were stationary and of uniform density, then at equilibrium, it would be a perfect sphere. But planets rotate, and so even the largest planets aren’t a perfect sphere.