Dark matter remains mysterious and… well… dark. While we don’t yet have a definite idea of what this cosmic “stuff” is made of, astronomers are learning more about its distribution throughout the Universe. Since we can’t see it directly, observers need to use indirect methods to detect it. One way is through gravitational lensing. Another is by looking for emissions from hydrogen gas associated with small-scale dark matter structures in the Universe.
NASA’s Lucy spacecraft launched almost one year ago, in October of 2021. Its journey is an ambitious one, and long. It’ll visit eight different asteroids in its planned 12-year mission. Two of them are main belt asteroids, and the other six are Jupiter Trojans, which share the gas giant’s orbit around the Sun.
Our galaxy has about 200 Globular Clusters (GCs,) and most of them are in the galaxy’s halo. Astronomers think most GCs were taken from dwarf galaxies and merged with the Milky Way due to the galaxy’s powerful gravity. That explains why so many of them are on the outskirts of the galaxy. But they’re not all in the halo. Some are towards the Milky Way’s galactic bulge. What are globular clusters doing there?
Roughly 5 billion years ago Earth was in the process of forming. Gas and dust gathered with the young Sun’s protoplanetary disk, likely nudged a bit by the resonant gravitational pull of Jupiter and other large worlds. One can imagine that as Earth formed it swept its orbit clear of debris, leaving a gap in the disk visible from light years away. While we know this tale is reasonably accurate, the idea that planets such as Earth always clear gaps in a protoplanetary disk likely isn’t.
When you launch humanity’s most powerful telescope, you expect results. The JWST has delivered excellent results by detecting ancient galaxies, identifying chemicals in exoplanet atmospheres, and peering into star-forming regions with more detail and clarity than any other telescope.
Despite its great oceans, Earth is not really an ocean world. It has less water than icy moons such as Europa and Enceladus, a relatively thin nitrogen-rich atmosphere, and vast continents that rise above sea level. A true ocean world would have no continents, a warm sea hundreds of kilometers deep, and a thick hydrogen and water-rich atmosphere. They are known as hydrogen-ocean planets or hycean worlds. While we’ve long thought they exist, the James Webb Space Telescope may now have found one.
When you look up in the night sky and find your way to the North Star, you are looking at Polaris. Not only is it the brightest star in the Ursa Minor constellation (the Little Dipper), but its position relative to the north celestial pole (less than 1° away) makes it useful for orienteering and navigation. Since the age of modern astronomy, scientists have understood that the star is a binary system consisting of an F-type yellow supergiant (Polaris Aa) and a smaller main-sequence yellow dwarf (Polaris B). Further observations revealed that Polaris Aa is a classic Cepheid variable, a stellar class that pulses regularly.
In the constellation Taurus, there is a cluster of a few hundred stars known as the Hyades. The cluster is just 150 light-years away, and it could be harboring a stellar-mass black hole.
The Moon was geologically active between 3.7 and 2.5 billion years ago, experiencing quakes, volcanic eruptions, and outgassing. Thanks to the Moon being an airless body, evidence of this past has been carefully preserved in the form of extinct volcanoes, lava tubes, and other features. While the Moon has been geologically inert for billions of years, it still experiences small seismic events due to tidal flexing (because of Earth’s gravitational pull) and temperature variations. These latter events happen regularly and are known as “moonquakes.”
In a recent study submitted to the Journal of the British Interplanetary Society for the 8th Interstellar Symposium special issue, which is due for publication sometime in 2024, Dr. Jacob Haqq-Misra, who is a senior research investigator and the Chief Operating Officer and co-founder at the Blue Marble Space Institute of Science, examines how future space exploration governing laws could evolve, either crewed or uncrewed and in the solar system or beyond. He views this study as an expansion of interplanetary governance models he previously discussed in his book, Sovereign Mars, to explore potential limits on space governance at interstellar distances.
Astronomers working with NASA’s Neil Gehrels Swift Observatory have spotted something unusual. The observatory’s X-Ray Telescope (XRT) has captured emissions from a supermassive black hole (SMBH) in a galaxy about 500 million light-years away. The black hole is repeatedly feeding on an unfortunate star that came too close.
Approximately every 80 years, a faint 10th magnitude star in the constellation of Corona Borealis dramatically increases its brightness. This star, T CrB, is known as a recurrent nova and last flared in 1946, peaking at magnitude 2.0, temporarily making it one of the 50 brightest stars in the night sky.
We have built telescopes in our backyards, and high upon remote mountains, and even launched telescopes into space. With each advancement in our technology, we have made amazing and surprising new discoveries about the Universe. So what should our next advance in observatories be? Based on a new paper on the arXiv, a good choice would be the lunar surface.
After NASA’s DART mission slammed into asteroid Dimorphous in September 2022, scientists determined the impact caused tons of rock to be ejected from the small asteroid’s surface. But more importantly, DART’s impact altered Dimorphos’ orbital period, decreasing it by about 33 minutes.
Earth and Mars are very much alike, but also very different. Among other things, scientists find that Earth is much more mineral-rich than the Red Planet. It has 6,000 different minerals. By contrast, Mars has only 161. That’s a big difference. How could this have happened?
In 1908, when an object entered the Earth’s atmosphere above the Podkamennaya Tunguska River, it flattened 80 million trees over nearly 2,200 square kilometers, and sent atmospheric shock waves reverberating around the world. Fortunately, this event was in a remote region and very few people were believed to be killed.
Measuring cosmic distances is a major challenge thanks to the fact that we live in a relativistic Universe. When astronomers observe distant objects, they are not just looking through space but also back in time. In addition, the cosmos has been expanding ever since it was born in the Big Bang, and that expansion is accelerating. Astronomers typically rely on one of two methods to measure cosmic distances (known as the Cosmic Distance Ladder). On the one hand, astronomers rely on redshift measurements of the Cosmic Microwave Background (CMB) to determine cosmological distances.
Spacecraft instruments are highly specialized and can take years to design, build, and test. But a last-minute hack to one of the instruments on the ESA’s Solar Orbiter has allowed the spacecraft to take some difficult observations it would otherwise have been unable to take.
The galaxies in our local Universe all have magnetic fields. Galactic magnetic fields can be generated by ionized gas within a galaxy, and these same magnetic fields affect the evolution of galaxies. But while modern galaxies have magnetic fields, did early ones? Astronomers are still trying to understand how galactic magnetic fields arise in young galaxies, but this can be a challenge without observational data. Now a team using data from the Atacama Large Millimeter/submillimeter Array (ALMA) has observed the magnetic field of a galaxy when the Universe was just 2.5 billion years old. The galaxy is known as 9io9. It takes 11 billion years for its light to reach us, making it the most distant galaxy for which we have observed a magnetic field.
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