Astronomers are watching two unusual black holes, each presenting phenomena that challenge current understanding of these cosmic giants. One, a “serial killer” black hole, is about to devour its second star within five years, while the other, part of the newly discovered triple system V404 Cygni, has disrupted long-held theories of black hole formation.

The Black Hole “Serial Killer” Reaches for Another Star

Located 215 million light-years from Earth, this supermassive black hole first caught scientists’ attention five years ago with a bright flare. The flare came from a star that had drifted too close to it, sparking what astronomers call a tidal disruption event, or AT1910qix. Gravitational forces stretched and tore apart the star, leaving part of its remains around the black hole and launching the rest into space.

Led by Dr Matt Nicholl of Queen’s University Belfast, a team of astronomers has tracked this remnant disc over several years using high-powered telescopes such as the Chandra X-ray Observatory and the Hubble Space Telescope. Recently, another star has started passing through this disc every 48 hours, creating bright X-ray bursts with each collision. Dr Nicholl describes it as similar to a diver creating splashes in a pool each time they hit the water, with the star as the diver and the disc as the pool.

“What’s uncertain is what will ultimately happen to this star,” Dr Nicholl said. “It could be pulled into the black hole, or it may eventually disintegrate from these repeated impacts.”

A Rare Triple Black Hole System in Cygnus

Meanwhile, in the constellation Cygnus, a rare triple system is raising questions about black hole origins. Known as V404 Cygni, this system includes a nine-solar-mass black hole and two orbiting stars, one much farther away than astronomers had thought possible. Kevin Burdge, an MIT research fellow, notes that a supernova typically pushes any distant companions too far to remain gravitationally bound. But in this system, a distant star orbits at a staggering 300 billion miles.

In their Nature paper, Dr Burdge and his team proposed that this black hole may have formed without a supernova explosion, possibly “quietly” collapsing without ejecting its nearby companions. This hypothesis has sparked interest among scientists, as it hints at new black hole formation processes yet to be fully understood.

Daniel Holz, an astrophysicist at the University of Chicago, noted that while unlikely, nature often defies assumptions. This discovery could open a new chapter in black hole research.

NASA’s Parker Solar Probe will make a close approach to Venus on Wednesday, marking the spacecraft’s seventh and final flyby of the planet. This manoeuvre will set the probe on a course for its historic plunge toward the sun, bringing it within 3.8 million miles of our star’s surface — closer than any human-made object has ventured. Nour Raouafi, Project Scientist at the Johns Hopkins University Applied Physics Laboratory, described this approach as “almost landing on a star,” likening it to the significance of the 1969 moon landing.

Venus Flybys as Critical Milestones

The Parker Solar Probe, launched in 2018, relies on gravitational assists from Venus to gradually reduce its distance from the sun, using the planet’s gravitational pull to adjust its orbit. Yanping Guo, Mission Design and Navigation Manager at the Johns Hopkins Applied Physics Laboratory, emphasised that this final Venus flyby is crucial in positioning the probe for its upcoming close encounter with the sun.

While designed for solar exploration, the probe’s instruments have provided valuable data on Venus. During previous flybys, Parker’s Wide-Field Imager (WISPR) managed to capture images through Venus’s thick atmosphere, revealing surface details like continents and plateaus. The probe also recorded emissions from Venus’s nightside, providing insights into its surface composition and temperature, which is around 860 degrees Fahrenheit (460 Celsius).

A Closer Look at Venusian Surface

This week’s flyby will allow scientists to point WISPR toward Venus once more to capture new surface images, including areas with varied landforms. Noam Izenberg, a planetary geologist at APL, noted that this close approach offers a unique chance to study differences in Venus’s surface features, potentially uncovering information about its geology and thermal properties.

Approaching the Sun’s Frontier

On December 24, the Parker Solar Probe will skim the sun’s outer layer at speeds of up to 430,000 miles per hour (692,010 km/h). Although mission control will lose contact during this close pass, engineers hope to receive a signal on December 27 confirming the probe’s success. This achievement could unlock significant insights into the sun’s outer atmosphere, its intense heat, and its magnetic dynamics, further advancing our understanding of solar phenomena.

In April 2029, asteroid Apophis will pass exceptionally close to Earth—at just 20,000 miles away, closer than many satellites. The encounter may trigger significant physical changes on the asteroid’s surface due to Earth’s gravitational pull, potentially causing landslides and tremors, according to a recent study. Apophis, a 340-meter, peanut-shaped asteroid named after the ancient Egyptian deity associated with chaos, is not expected to impact Earth. However, this flyby could offer scientists a unique opportunity to observe how gravitational forces affect small celestial bodies.

New Insights into Surface Alterations

The study, currently available on the arXiv preprint database, has been accepted for publication in The Planetary Science Journal. Asteroid scientist Ronald-Louis Ballouz from Johns Hopkins University Applied Physics Laboratory and his team conducted computational simulations of Apophis to predict the changes Earth’s gravity might induce. Ballouz notes that while meteoroids constantly weather asteroid surfaces in space, close planetary encounters can also alter an asteroid’s appearance. The gravitational pull from Earth is expected to disrupt Apophis’ surface by triggering tremors, lifting rocks, and creating visible patterns.

Predicted Surface Shifts and Landslides

The team’s models suggest that Apophis will experience surface tremors starting an hour before it reaches its closest approach to Earth, potentially dislodging boulders. Although Apophis’ own gravity is weak, this gravitational “shaking” could loft rocks briefly before they fall back, forming new surface features. Additionally, Apophis’ irregular rotation, or “tumbling,” might accelerate or slow down due to Earth’s gravitational influence. These shifts in tumbling could further destabilise rocks over time, potentially leading to gradual landslides that shape the asteroid’s surface over tens of thousands of years.

Future Observations with NASA’s OSIRIS-APEX Mission

Scientists hope to verify these findings when NASA’s OSIRIS-APEX spacecraft studies Apophis in 2029. Repurposed from its earlier mission to the asteroid Bennu, OSIRIS-APEX is set to examine Apophis’ chemical composition and surface features over an 18-month mission. This research could help solve longstanding questions about how gravitational encounters refresh asteroid surfaces, providing new insights into asteroid dynamics and planetary formation processes.