Follow the Fall 2023 Return of Comet 103P Hartley

Comet Hartley
Comet 103/P Hartley encounters the Perseus Double Cluster in 2010. Image credit: Kevin Jung

Catch periodic cosmic interloper 103P Hartley while you can.

Periodic comets are like old friends, back for a visit. We have a get together with just such a denizen of the cometary league, as Comet 103P Hartley makes a favorable apparition in late 2023.

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Did a Comet Airburst Destroy a Native American Community?

Artist impression of the Tunguska event.

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.

But research published in Nature’s Scientific Reports in 2022 by Tankersly et al. suggested that a similar, but even more powerful comet airburst in the Ohio River Valley may have been the death knell for the Hopewell civilization, some 1,600-1,700 years ago just outside modern day Cincinnati. However, other scientists rejected the arguments.

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Another New Way to Measure Distance in the Universe: Baryon Acoustic Oscillations

An artist's concept of the latest, highly accurate measurement of the Universe from BOSS. The spheres show the current size of the "baryon acoustic oscillations" (BAOs) from the early universe, which have helped to set the distribution of galaxies that we see in the universe today. Galaxies have a slight tendency to align along the edges of the spheres — the alignment has been greatly exaggerated in this illustration. BAOs can be used as a "standard ruler" (white line) to measure the distances to all the galaxies in the universe. Credit: Zosia Rostomian, Lawrence Berkeley National Laboratory

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.

Conversely, they will rely on local observations using parallax measurements, variable stars, and supernovae. Unfortunately, there is a discrepancy between redshift measurements of the CMB and local measurements, leading to what is known as the Hubble Tension. To address this, a team of astronomers from several Chinese universities and the University of Cordoba conducted a two-year statistical analysis of one million galaxies. From this, they’ve developed a new technique that relies on Baryon Acoustic Oscillations (BAO) to determine distances with a greater degree of precision.

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The Space Station is Getting Gigabit Internet

NASA's ILLUMA-T payload communicating with LCRD over laser signals. Credit: NASA/Dave Ryan

Aboard the International Space Station (ISS), astronauts and cosmonauts from many nations are performing vital research that will allow humans to live and work in space. For more than 20 years, the ISS has been a unique platform for conducting microgravity, biology, agriculture, and communications experiments. This includes the ISS broadband internet service, which transmits information at a rate of 600 megabits per second (Mbps) – ten times the global average for internet speeds!

In 2021, NASA’s Space Communications and Navigation (SCaN) began integrating a technology demonstrator aboard the ISS that will test optical (laser) communications and data transfer. This system currently consists of Laser Communications Relay Demonstration (LCRD) and will soon be upgraded with the addition of the Integrated LCRD Low Earth Orbit User Modem and Amplifier Terminal (ILLUMA-T). Once complete, this system will be the first two-way, end-to-end laser relay system, giving the ISS a gigabit internet connection!

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TESS Finds a Planet That Takes 482 Days to Orbit, the Widest it’s Seen so Far

An artist's rendition of the two planets and star in the TOI-4600 system. One of them has the longest orbit of any planet yet found by TESS. Image Credit: Tedi Vick

We’re rapidly learning that our Solar System, so familiar to us all, does not represent normal.

A couple of decades ago, we knew very little about other solar systems. Astronomers had discovered only a handful of exoplanets, especially around pulsars. But that all changed in the last few years.

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JWST Gazes into the Dark Molecular Clouds at the Heart of the Milky Way

The Central Molecular Zone; the Heart of the Milky Way. Image Credit: Henshaw / MPIA

There’s an unusual object near the Milky Way’s heart that astronomers call “The Brick.” It’s a massive cloud of gas called an infrared dark cloud (IDC). The Brick is dense and turbulent like others of its type, but for some reason, it shows few signs of star formation.

Why?

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Some Galaxies Contain Double Supermassive Black Holes

A Hubble Space Telescope view of M87's core and its jet. it points nearly directly at us and is also known as a blazar. Astronomers are studying other blazars that have meandering jets and think that binary black holes may be hidden inside some of them. Courtesy STScI.
A Hubble Space Telescope view of M87's core and its jet. it points nearly directly at us and is also known as a blazar. Astronomers are studying other blazars that have meandering jets and think that binary black holes may be hidden inside some of them. Courtesy STScI.

Blazars occupy an intriguing spot in the cosmic zoo. They’re bright active galactic nuclei (AGN) that blast out cosmic rays, are bright in radio emission, and sport huge jets of material traveling in our direction at nearly the speed of light. For some blazars, their jets look curvy and snaky and astronomers have questions.

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A Bizarre Pulsar Switches Between Two Brightness Modes. Astronomers Finally Figured Out Why.

Credit: ESO/M. Kornmesser

Pulsars are the lighthouses of the universe. These rotating dead stars shoot twin jets of radiation from their poles, usually with a predictable rhythm. But sometimes pulsars behave strangely, and one pulsar in particular has had astronomers scratching their heads for years. It’s called PSR J1023+0038, and a decade ago, it shut off its jets and began oscillating between two brightness levels in an unpredictable pattern. Now, scientists think they understand why: it is busy eating a neighboring star.

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Is Humanity Ready to Realize the Dream of Interstellar Travel?

The 8th Interstellar Symposium was held from July 10th to 13th at McGill University. Credit: Interstellar Research Group (IRG)

For generations, humans have dreamed, speculated, and theorized about the possibility of journeying to distant stars, finding habitable planets around them, and settling down. In time, the children of these bold adventurers would create a new civilization and perhaps even meet the children of Earth. People could eventually journey from one world to another, cultures would mix, and trade and exchanges would become a regular feature. The potential for growth that would come from these exchanges – intellectually, socially, politically, technologically, and economically – would be immeasurable.

Expanding humanity’s reach beyond the Solar System is not just the fevered dream of science fiction writers and futurists. It has also been the subject of very serious scientific research, and interest in the subject is again on the rise. Much like sending crewed missions to Mars, establishing permanent outposts on the Moon, and exploring beyond cislunar space with human astronauts instead of robots – there is a growing sense that interstellar travel could be within reach. But just how ready are we for this bold and adventurous prospect? Whether we are talking about probes vs. crews or technological vs. psychological readiness, is interstellar travel something we are ready to take on?

This was a central question raised at a public outreach event aptly named “Interstellar Travel: Are We Ready?” that took place at the 8th Interstellar Symposium: In Light of Other Suns, held from July 10th to 13th at the University of McGill in Montreal, Quebec. The symposium was hosted by the Interstellar Research Group (IRG), the International Academy of Astronautics (IAA), and Breakthrough Initiatives – in coordination with the University of McGill – and featured guest speakers and luminaries from multiple disciplines – ranging from astronomy and astrophysics to astrobiology, geology, and cosmology.

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Did this Supernova Explode Twice?

Artist view of a binary system before a type Ia supernova. Credit: Adam Makarenko/W. M. Keck Observatory

All supernovae are exploding stars. But the nature of a supernova explosion varies quite a bit. One type, named Type 1a supernovae, involves a binary star where one of the pair is a white dwarf. And while supernovae of all types usually involve a single explosion, astronomers have found something that breaks that mould: A Type 1a supernova that may have detonated twice.

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