The James Webb Space Telescope (JWST) has captured the sharpest infrared images to date of a zoomed-in portion of one of the most distinctive objects in our skies, the Horsehead Nebula. The observations show the top of the “horse’s mane” or edge of this iconic nebula in a whole new light, capturing the region’s complexity with unprecedented spatial resolution.

The new images show part of the sky in the constellation Orion (The Hunter), in the western side of a dense region known as the Orion B molecular cloud. Rising from turbulent waves of dust and gas is the Horsehead Nebula, otherwise known as Barnard 33, which resides roughly 1,300 light-years away.

The nebula formed from a collapsing interstellar cloud of material, and glows because it is illuminated by a nearby hot star. The gas clouds surrounding the Horsehead have already dissipated, but the jutting pillar is made of thick clumps of material and therefore is harder to erode. Astronomers estimate that the Horsehead has about five million years left before it too disintegrates. Webb’s new view focuses on the illuminated edge of the top of the nebula’s distinctive dust and gas structure.

The Horsehead Nebula is a well-known photodissociation region, or PDR. In such a region, ultraviolet (UV) light from young, massive stars creates a mostly neutral, warm area of gas and dust between the fully ionized gas surrounding the massive stars and the clouds in which they are born. This UV radiation strongly influences the chemistry of these regions and acts as a significant source of heat.

These regions occur where interstellar gas is dense enough to remain mostly neutral, but not dense enough to prevent the penetration of UV light from massive stars. The light emitted from such PDRs provides a unique tool to study the physical and chemical processes that drive the evolution of interstellar matter in our galaxy, and throughout the universe from the early era of vigorous star formation to the present day.

Due to its proximity and its nearly edge-on geometry, the Horsehead Nebula is an ideal target for astronomers to study the physical structures of PDRs and the molecular evolution of the gas and dust within their respective environments, and the transition regions between them. It is considered one of the best regions in the sky to study how radiation interacts with interstellar matter.

Thanks to JWST’s MIRI and NIRCam instruments, an international team of astronomers has revealed for the first time the small-scale structures of the illuminated edge of the Horsehead. As UV light evaporates the dust cloud, dust particles are swept out away from the cloud, carried with the heated gas. Webb has detected a network of thin features tracing this movement. The observations have also allowed astronomers to investigate how the dust blocks and emits light, and to better understand the multidimensional shape of the nebula.

Next, astronomers intend to study the spectroscopic data that have been obtained to gain insights into the evolution of the physical and chemical properties of the material observed across the nebula.

These observations were taken for the JWST GTO program 1192 and the results were published 29 April 2024 in Astronomy & Astrophysics.

Source: Space Telescope Science Institute news release.

For the first time in five months, NASA’s Voyager 1 spacecraft is returning usable data about the health and status of its onboard engineering systems. The next step is to enable the spacecraft to begin returning science data again. The probe and its twin, Voyager 2, are the only spacecraft to depart the Solar System and fly in interstellar space.

Voyager 1 stopped sending readable science and engineering data back to Earth on 14th November 2023, although ground controllers could tell the spacecraft was still receiving their commands and otherwise operating normally. In March, the Voyager engineering team at NASA’s Jet Propulsion Laboratory in Southern California confirmed that the issue was tied to one of the spacecraft’s three onboard computers, called the Flight Fata Subsystem (FDS). The FDS is responsible for packaging the science and engineering data before it’s sent to Earth.

The team discovered that a single chip responsible for storing a portion of the FDS memory — including some of the FDS computer’s software code — isn’t working. The loss of that code rendered the science and engineering data unusable. Unable to repair the chip, the team decided to place the affected code elsewhere in the FDS memory. But no single location is large enough to hold the section of code in its entirety.

So they devised a plan to divide the affected code into sections and store those sections in different places in the FDS. To make this plan work, they also needed to adjust those code sections to ensure that they all still function as a whole. Any references to the location of that code in other parts of the FDS memory needed to be updated as well.

The team started by singling out the code responsible for packaging the spacecraft’s engineering data. They sent it to its new location in the FDS memory on 18th April. A radio signal takes about 22.5 hours to reach Voyager 1, which is over 15 billion miles (24 billion kilometres) from Earth, and another 22.5 hours for a signal to come back to Earth. When the mission flight team heard back from the spacecraft on 20th April, they saw that the modification worked: For the first time in five months, they have been able to check the health and status of the spacecraft.

Voyager 2 continues to operate normally. Launched over 46 years ago, the twin Voyager spacecraft are the longest-running and most distant spacecraft from Earth in history. Before the start of their interstellar exploration, both probes flew by Saturn and Jupiter, and Voyager 2 flew by Uranus and Neptune.

Source: JPL News Release

A lander built by the Houston-based company Intuitive Machines touched down near the Moon’s South Pole on Thursday. It was the first lunar landing by a US spacecraft in more than 50 years and the first commercially-operated vehicle to successfully reach the surface.

The Odysseus lander, also known as IM-1, fired its main engine continuously for 10 minutes before touching down at 11:23pm GMT. It’s the first time a methane-oxygen propulsion system has been used on a space exploration mission. During Thursday’s descent the engine was gradually throttled down to bring the craft to a soft landing.

There were some anxious moments when communications with Odysseus were lost. After several minutes a weak signal from the craft’s high gain antenna was detected and that was good enough to declare a successful landing.

“We can confirm without a doubt our equipment is on the surface of the Moon and we are transmitting,” said flight director Tim Crain.

Later Mission Control started receiving data, confirming the spacecraft, which is about the size of an old-style telephone box, was standing upright at its landing site, near the crater Malapert A, about 300 km from the Moon’s South Pole.

It was the first commercially built and operated lander to successfully reach the surface after private missions from Israel, Japan and, most recently, the U.S. company Astrobotic all ended in failure.

Astrobotic’s Peregrine and Intuitive Machines Odysseus missions were funded in part by NASA’s Commercial Lunar Payload Services (CLPS) programme which is designed to pave the way for the planned Artemis missions with astronauts aboard.

Odysseus is carrying six NASA payloads and a camera built by students that was to be jettisoned right before touchdown to capture views of the landing. NASA and Intuitive Machines are due to hold a news conference on Friday when the first images from the lander might be revealed.

The first colour images from the European Space Agency’s Euclid space telescope were unveiled 7 November, providing razor-sharp views of the Perseus galaxy cluster, two nearby galaxies, the Horsehead Nebula and a globular cluster.

“We have never seen astronomical images like this before, containing so much detail,” Euclid project scientist René Laureijs said in an ESA release accompanying the photos.

“They are even more beautiful and sharp than we could have hoped for, showing us many previously unseen features in well-known areas of the nearby Universe. Now we are ready to observe billions of galaxies, and study their evolution over cosmic time.”

The wide-angle view of the Perseus cluster, one of the largest structures in the known universe, is particularly striking, showing 1,000 or more member galaxies and another 100,000 or so in the distant background.

Euclid’s view of the Horsehead Nebula also was striking because it rivals the view from larger telescopes yet took just one hour to capture in a single frame.

While Euclid’s relatively small primary mirror is much less powerful than Hubble’s or the James Webb Space Telescope, the wider field of view, a 600-megapixel visible light camera and a 64-megapixel infrared spectrometer will allow it to discern the shape and evolution of galaxies over the past 10 billion years.

The $1.5 billion observatory is designed to probe the nature of dark energy, the mysterious force speeding up the expansion of the universe, and dark matter, the unseen material holding galaxies together and shaping their evolution.

By studying subtle changes in the light from selected galaxies, scientists hope to observe the transition from the Big Bang’s initial gravity-driven deceleration to the era of accelerated expansion under the emerging dominance of dark energy some five billion years ago. At the same time, they expect to map the influence of dark matter on galactic structure.

“Dark matter pulls galaxies together and causes them to spin more rapidly than visible matter alone can account for,” said ESA science director Carole Mundell. “Dark energy is driving the accelerated expansion of the Universe.

“Euclid will make a leap in our understanding of the cosmos as a whole, and these exquisite Euclid images show that the mission is ready to help answer one of the greatest mysteries of modern physics.”

It will take Euclid six years to complete a 3D map of the sky around the Milky Way, generating an estimated 100 gigabytes of data per day, or some 70,000 terabytes over the course of the mission.

One sure sign that summer is almost over and longer autumnal nights are taking over from more balmy late-summer evenings is the grand appearance in September’s late-evening southern sky of the Great Square of Pegasus, the winged-horse’s familiar asterism (star pattern). The Square is well up in the eastern sky as astronomically dark skies fall at mid-month and its centre culminates at around 1am BST (midnight UT) at a very favourable altitude of 60 degrees.

How to observe

The four stars marking the corners of the Square all shine at second- or third-magnitude, so it’s easy to see it even from light-polluted locations. Beginners often remark that the Square appears larger than expected; it spans roughly 15 degrees along each side and is about 20 degrees across diagonally.

Only three of the stars actually belong to Pegasus. The top-left (north-eastern) star of the Square is alpha (α) Andromedae (Alpheratz), the brightest star in the constellation Andromeda. At one time it had two designations, alpha Andromedae and delta (δ) Pegasi, but when the constellation boundaries were defined by the International Astronomical Union (IAU) in 1922, Alpheratz was assigned to Andromeda and the name delta Pegasi fell into disuse (at least by professional astronomers). The three other stars of the Square are among the brightest in the constellation: magnitude +2.45 Markab (alpha [α] Pegasi) lies at the bottom right (south-western) corner), magnitude +2.4 Scheat (beta [β] Pegasi) sits at top right (north-west), and magnitude +2.8 Algenib (gamma [γ] Pegasi) marks the bottom left (south-eastern) corner.

Lying within the Square, about 2.5 degrees north-west of Algenib, is NGC 7814 (Caldwell 43), a very nice edge-on galaxy shining at magnitude +10.5. It is sometimes called the ‘Little Sombrero’, as it is reminiscent of the magnificent Sombrero Galaxy (Messier 104) in Virgo, but NGC 7814 is much smaller, spanning only 6.3 × 2.6 arcminutes. NGC 7814 is an easy capture for a 150mm (six-inch) telescope.

NGC 7741 is another galaxy located within the confines of the Square, found 6 degrees south-west of Alpheratz. It’s an attractive imaging target, but is a real challenge for a 250mm (10-inch) telescope, glowing at magnitude +11.4, a magnitude or so fainter than NGC 7814, across its 4 x 2.8 arcminute form.

One final target of note within the Square is the galaxy grouping of NGC 7769, 7770 and 7769. The former and latter are nice eleventh-magnitude spirals that can be observed through apertures in the 250-300mm (10- to 12-inch) range, but the real appeal is the group’s attractiveness in deep images. 

How dark’s your sky?

A good measure of your sky quality is to count the number of stars that you can see within the Great Square of Pegasus – not including the corner stars of the Square itself. You can work out your limiting magnitude according to the number of stars seen using the following table.

It’s hang on to your observing hats time once more as a brand new comet, C/2023 P1 (Nishimura), discovered on 11 August, promises a dramatic brightening as it hurtles towards the Sun. However, in typical cometary fashion, its behaviour is hard to predict on its first and only visit to the Sun’s harsh environs. There’s a chance it will disintegrate and fizzle out.

Presently Comet C/2023 P1 (Nishimura) lies in the pre-dawn sky tracking north-eastwards among the stars of Gemini. Observing reports are sketchy in the first week or so, but it is shining at around magnitude +9.5 and on discovery was reported with a coma of 5 arcminutes in angular size and a tail eight arcminutes long. Nishimura will be at its closest to Earth, a distance of around 127.1 million kilometres (0.85 AU), on 13 September, and reach perihelion on 18 September, when it lies 32.9 million kilometres (0.22 AU) from the Sun.

When to observe the comet

The comet remains in the pre-dawn sky up to 13 September. A small telescope should easily bag it, provided your observing site has a good horizon to the east-southeast and isn’t too badly afflicted by light pollution. The Moon is well out of the way until early September.

On 20 August at 4.25am, about 90 minutes before sunrise and at the beginning of nautical twilight from London (with the Sun 12° below the horizon), Comet C/2023 P1 (Nishimura) lies around 13° up, some 3° south-east of the magnitude +3.5 star Wasat (delta Geminorum). The comet should be easier to detect on the pre-dawn of 26 August, as it lines up nicely with Gemini’s bright stars Castor and Pollux, the comet located 6.7° below Pollux, the southerly twin. It’s a little better placed now, 4° higher in the sky, with the Minor Planet Center predicting a brightening of one magnitude.

By the end of August, Comet C/2023 P1 (Nishimura) lies in Cancer, maintaining its altitude and located around 4° north-northwest of the Beehive cluster (Messier 44), the brilliant open cluster. If it continues to brighten at the predicted rate the comet will shine at around magnitude +7.5.

Into September: losing altitude but brightening faster

During the first week of September Comet C/2023 P1 (Nishimura) begins to lose altitude as it gets ever closer to the Sun, but compensates by an increased rate of brightening. It should be visible through binoculars at this stage.

The pre-dawn of 7 September finds the comet in Leo, scraping north past magnitude +3 epsilon Leonis as it lies around 13° high in London at 5.05am. A few mornings later Comet C/2023 P1 (Nishimura) dips below 10° altitude as it starts to plunge southwards, now moving across the sky over four times faster than at discovery.

Into the early evening sky

After closest approach to Earth on 13 September, Comet C/2023 P1 (Nishimura) transfers to the early-evening sky, though its elongation from the Sun is only 12 to 15 degrees. There is a slim chance to spot it in strong twilight about 40 minutes after sunset between 13th and 18th, lying just 6° or so high in the west-northwest. Some estimates have Comet C/2023 P1 (Nishimura) at magnitude +2.8 at this time; even if that’s correct, it will be hard to see.

If it survives perihelion passage, Comet C/2023 P1 (Nishimura) continues to plunge south for the rest of the year. Observers in the Southern Hemisphere can observe it in twilit conditions; from Sydney, Australia, the comet appears low in the pre-dawn north-eastern sky up to around 25 August, but after that the comet is not observable again until late October, when its low in the pre-dawn among the stars of Hydra, not far from globular cluster M68. However, it now shines fainter than magnitude +10.

NASA’s Deep Space Network has detected a faint carrier signal from the Voyager 2 probe just a few days after losing contact because of erroneous commands that inadvertently caused the spacecraft to turn slightly away from Earth.

While Voyager 2’s 3.7-metre (12-foot) dish antenna is still misaimed and the signal is too weak to carry any data, it indicates the spacecraft is still alive, functional and on course.

Flight controllers will attempt to beam new commands from the DSN at a much higher power level in an attempt to coax a realignment with Earth. If that fails, the probe’s computer periodically executes stored commands to reset its alignment. The next reset is expected in October.

The European Space Agency’s Euclid space telescope, launched 1 July atop a SpaceX Falcon 9 rocket, has reached its operational location at Lagrange Point 2, a gravitationally stable region 1.5 million kilometres (1 million miles) from Earth.

Initial test images show the spacecraft’s VISual imager (VIS) and its Near-infrared Imaging Spectrometer and Photometer (NISP) are operating in fine fashion, producing razor-sharp, wide-angle views of countless stars and galaxies. The raw images show streaks from cosmic rays, but such artefacts will be removed when science images are processed.

“After more than 11 years of designing and developing Euclid, it’s exhilarating and enormously emotional to see these first images,” said project manager Giuseppe Racca. “It’s even more incredible when we think that we see just a few galaxies here, produced with minimum system tuning. The fully calibrated Euclid will ultimately observe billions of galaxies to create the biggest ever 3D map of the sky.”

Said Yannick Mellier, lead of the multi-agency Euclid research consortium: “The outstanding first images obtained using Euclid’s visible and near-infrared instruments open a new era to observational cosmology and statistical astronomy. They mark the beginning of the quest for the very nature of dark energy, to be undertaken by the Euclid Consortium.”

The $1.5 billion Euclid is a first-of-a-kind attempt to pin down the nature of dark matter, the unknown material pervading the cosmos, and dark energy, the mysterious repulsive force that is speeding up the expansion of the universe.

By studying subtle changes in the light from galaxies over the past 10 billion years, Euclid’s cameras will help scientists find out if dark energy is consistent with an unchanging “cosmological constant” once predicted by Einstein’s theory of general relativity or whether the current understanding of gravity needs revision.

Euclid also will study the nature of dark matter by analysing the shapes of some 1.5 billion galaxies to determine how they have been distorted by clouds of unseen dark matter filling the space between Euclid and its targets.

“It is fantastic to see the latest addition to ESA’s fleet of science missions already performing so well,” said ESA Director General Josef Aschbacher. “I have full confidence that the team behind the mission will succeed in using Euclid to reveal so much about the 95 percent of the Universe that we currently know so little about.”

On 21 July, flight controllers in Pasadena, California, uplinked a series of commands that inadvertently caused the Voyager 2 spacecraft to aim itself and its high-gain antenna at a point in space 2 degrees away from Earth. Since then, the probe has been incommunicado, unable to receive commands or beam telemetry and science data to the ground.

While the misalignment is relatively minor, at Voyager 2’s distance from Earth – 19.9 billion kilometres, or 12.4 billion miles – it’s more than enough to keep the spacecraft’s increasingly weak signal, less than a billionth of a billionth of a watt by the time it reaches Earth, from hitting NASA’s Deep Space Network antennas.

Not to worry. NASA says Voyager 2 is programmed to reset its orientation several times a year to keep its antenna precisely aimed. The next reset is expected on 15 October, when flight controllers will be standing by to resume two-way communications. Round-trip travel time for signals to and from Voyager 2: about 37 hours.

Launched in 1977, Voyager 1 departed the solar system after flybys of Jupiter and Saturn. Voyager 2 followed suit after flybys of Jupiter Saturn, Uranus and Neptune. Both have departed the solar system and are now sailing through interstellar space, racing away from the Sun at more than 54,700 kph (34,000 mph).

Astronomers have found a white dwarf with two faces, one side dominated by hydrogen and the other by helium. Appropriately enough, they’ve dubbed it Janus after the two-faced Roman god of transition and duality.

“The surface of the white dwarf completely changes from one side to the other,” said Ilaria Caiazzo, a postdoctoral scholar at Caltech who led a study describing the findings in the journal Nature. “When I show the observations to people, they are blown away.”

White dwarfs are the remnants of stars like our Sun that have used up their nuclear fuel, swelling to become red giants before blowing off their outer layers. The cores then collapse, forming slowly cooling planet-size dwarf stars.

Heavier elements sink into the interior while lighter elements like hydrogen float to the top. Over time, as the dwarf cools, the materials mix together and in some cases, helium can become more prevalent.

The Janus dwarf was discovered by the Zwicky Transient Facility at Caltech’s Palomar Observatory near San Diego, California. Caiazzo was searching for highly magnetised white dwarfs when her team took a closer look at a candidate that showed rapid brightness changes.

Using the CHIMERA instrument at Palomar and the HiPERCAM on the Gran Telescopio Canarias in the Canary Islands, they found it was rotating on its axis once every 15 minutes. Subsequent spectroscopic observations using the W.M. Keck Observatory in Hawaii showed one side was dominated by hydrogen and the other side by helium.

Baffled, the team came up with two possible explanations, both involving the dwarf’s magnetic field.

“Magnetic fields around cosmic bodies tend to be asymmetric, or stronger on one side,” Caiazzo said. “Magnetic fields can prevent the mixing of materials. So, if the magnetic field is stronger on one side, then that side would have less mixing and thus more hydrogen.”

Another possibility: the magnetic fields could change the pressure and density of the gases. Said co-author James Fuller, professor of theoretical astrophysics at Caltech: “The magnetic fields may lead to lower gas pressures in the atmosphere, and this may allow a hydrogen ‘ocean’ to form where the magnetic fields are strongest.”

“We don’t know which of these theories are correct, but we can’t think of any other way to explain the asymmetric sides without magnetic fields.”