SPACE / COSMOS
Meet the remarkable nebula shaped like a Christmas tree
By Dr. Tim Sandle
December 25, 2025
Arrayed with a simple triangular outline above S Monocerotis, the stars of NGC 2264 are popularly known as the Christmas Tree star cluster. Image Credit & Copyright: Michael Kalika, NASA (with permission).
To mark the Christmas period, astronomers from NASA have drawn attention to a spectacular region of space that looks remarkably like a glowing Christmas tree (in the shape of a Nordic tree and lit with merry lights).
Known as NGC 2264, this distant star-forming region sits about 2,700 light-years away and is filled with newborn stars lighting up clouds of gas and dust. The stars form a triangular shape called the Christmas Tree cluster, crowned by the dramatic Cone Nebula and wrapped in the swirling Fox Fur Nebula below.
This region, the constellation Monoceros, is positioned near the celestial equator and close to the flat disk of the Milky Way, which makes it visible from many locations on Earth during certain seasons. The binary star system A0620-00 in the constellation of Monoceros is at a distance of roughly 3,300 light-years (1,000 parsecs) away.
The combination of these features creates a festive cosmic scene spanning nearly 80 light-years, showing how young stars shape their surroundings on a truly galactic scale.
Why does the image resemble a Christmas tree?
The scene, as captured in the iages, is filled with enormous clouds of interstellar gas and dust, the raw ingredients needed to form stars. As young stars ignite within these clouds, they release intense energy that causes the surrounding hydrogen gas to glow red.
These glowing regions are known as emission nebulae. An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. Here, the most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star.
Dark dust clouds thread through the area as well, blocking light from stars behind them and creating dramatic shadows. In places where this dust lies close to hot, newly formed stars, it reflects their light instead of absorbing it, producing soft blue regions called reflection nebulae.
Describing the Christmas Tree
In a research note, the scientists behind the observation state: “Near the center of NGC 2264 is S Monocerotis, a bright variable star whose brightness changes over time. This star is surrounded by a noticeable blue glow caused by reflected starlight from nearby dust. Above S Monocerotis, a group of young stars forms a simple triangular pattern. Because of this distinctive shape, the cluster has become widely known as the Christmas Tree star cluster.”
At the top of this star filled scene sits the Cone Nebula, a tall structure of gas and dust shaped by powerful radiation from nearby young stars. Beneath it spreads a tangled and glowing cloud called the Fox Fur Nebula, named for its textured, fur like appearance. These features are constantly being reshaped as energetic starlight pushes and sculpts the surrounding material.
The Cone Nebula spans about 7 light-years and is mainly composed of molecular hydrogen gas and interstellar dust. The Christmas Tree Cluster contains more than 600 young stars, some of which are spectral types O and B that emit intense ultraviolet radiation. This radiation interacts with the surrounding molecular cloud, causing photo-ionization of the gas and the formation of an H II region.
SCIENCE EDITOR
December 25, 2025
This is a colored view of the C-type asteroid 162173 Ryugu, seen by the ONC-T camera on board of Hayabusa2. Source - ISAS/JAXA, CC SA 4.0.
Scientists are assessing the makeup of carbon-rich asteroids to see whether they could one day fuel space exploration—or even be mined for valuable resources. For long duration missions to the Moon and Mars, using materials found in space could significantly reduce the need for supplies launched from Earth. However, improved identification and classification is required to track asteroids altered by water and rich in water bearing minerals.
What are asteroids really made of? New analysis brings space mining closer to reality.
By analysing rare meteorites that naturally fall to Earth, researchers have uncovered clues about the chemistry, history, and potential usefulness of these ancient space rocks. While large-scale asteroid mining is still far off, the study highlights specific asteroid types that may be promising targets, especially for water extraction.
The research team is led by the Institute of Space Sciences (ICE-CSIC) and here scientists examined samples linked to C-type asteroids, carbon rich objects that are believed to be the original sources of carbonaceous chondrites.
C-type asteroids are the most common type, making up about 75% of all known asteroids in the solar system. Their composition includes carbon compounds, silicate minerals, water, and organic materials.
Carbonaceous chondrites arrive on Earth naturally, but they account for only about 5% of all meteorite falls. Many are extremely fragile and break apart before they can be recovered, which makes them especially rare. When they are found, it is often in desert environments such as the Sahara or Antarctica, where preservation conditions are favourable
Source – NASA/JPL-Caltech/UCLA. Public Domain
Digging into the research data
The ICE-CSIC team selected and carefully characterized asteroid related samples before sending them for detailed chemical analysis. The measurements were performed using mass spectrometry at the University of Castilla-La Mancha. This work allowed the researchers to determine the precise chemical make-up of the six most common types of carbonaceous chondrites and assess whether extracting materials from their parent asteroids could one day be practical.
The Asteroids, Comets, and Meteorites research group at ICE-CSIC has spent more than a decade studying the physical and chemical properties of asteroid and comet surfaces.
While many small asteroids are covered in loose surface material known as regolith, collecting small samples is very different from extracting resources at scale.
Regolith is a blanket of unconsolidated, loose, heterogeneous superficial deposits covering solid rock.
The results arguably strengthen the case that these asteroids could serve as important material reservoirs. The findings also help scientists identify where these meteorites came from and support planning for future space missions and resource extraction technologies.
While asteroids contain other minerals of interest, most asteroids only have relatively small abundances of precious elements, and therefore the objective of the research has also been to understand to what extent their extraction would be viable for a government or commercial operation.
Need for classification
The main asteroid belt contains an enormous range of objects, and understanding what resources they hold requires careful classification. Asteroid composition varies widely due to their long and complex histories, influenced by their evolutionary history, particularly collisions and close approaches to the Sun. Certain asteroids, from which hydrated carbonaceous chondrites originate, will have fewer metals in their native state, but they contain water, meaning that different asteroids will provide different benefits for future space explorers and space miners.
Overall, given current technology and costs, the researchers are of the view that mining undifferentiated asteroids — the primordial remnants of the solar system’s formation, considered the progenitor bodies of chondritic meteorites — remains impractical for now. However, with an improved classification system and identification, a future state will be to pinpoint very specific asteroids of economic or practical significance.
Asteroids are not subject to national appropriation according to the Outer Space Treaty. Whether they are owned by no one or by all of humanity under common heritage is still a matter of legal debate.
The findings appear in the journal Monthly Notices of the Royal Astronomical Society, titled “Assessing the metal and rare earth element mining potential of undifferentiated asteroids through the study of carbonaceous chondrites.”
Modeling of electrostatic and contact interaction between low-velocity lunar dust and spacecraft
Beijing Institute of Technology Press Co., Ltd
image:
Fig. 1. A diagram illustrating the phenomenon of charged dust particles being attracted or repulsed to the charged spacecraft on the lunar surface. Background image republished from ESA-ATG.
view moreCredit: Space: Science & Technology
In a research article recently published in Space: Science & Technology, scholars from Beijing Institute of Technology, China Academy of Space Technology, and Chinese Academy of Sciences together propose a theoretical model aimed at comprehensively analyzing the dynamics of adhesion and escape phenomena occurring during low-velocity impacts between charged dust particles and spacecrafts enveloped by a plasma sheath which serves as a crucial step toward understanding the mechanism of lunar dust pollution.
First, the model of electrostatic force is demonstrated. As depicted in Fig. 1, dominated by the photoelectron effect induced by solar ultraviolet and x-ray radiation, the spacecraft and lunar regolith on lunar dayside typically charge positive. As a result, a photoelectron sheath forms above the surface. On the nightside, the spacecraft and regolith usually are negatively charged since the collection of plasma electrons. Due to the higher average thermal velocity of electrons compared to ions, a Debye sheath consequently forms around the vehicle. Besides, the exposure to the solar wind, the lunar plasma wake, and plasma in the magnetotail lobes and plasma sheet also electrically charges the spacecraft and regolith. This study only focuses on the interaction between charged particles and spacecraft within the confines of the plasma sheath, while the interaction between dust with plasma can be safely neglected. Considering the significant difference in size between the vehicle and the dust particle, the vehicle can be assumed as an infinite conducting plane coated with a dielectric layer, as depicted in Fig. 2. A dielectric dust particle, characterized by its radius Rp, uniform surface charge density σp, and permittivity εp, is positioned at a distance d above the surface. The distance between the surface of the coating and the shell is triple the Debye length (Rd) of plasma sheath. The potential of the shell is denoted by κ and is usually defined as the reference potential. The decay of potential in the sheath follows an exponential pattern. Hence, the distribution of the electric potential field within the plasma sheath can be expressed as: φ0 = κ exp[-(z-3Rd)/Rd], E0 = κ/Rd·exp[-(z-3Rd)/Rd], 0 ≤ z ≤ 3Rd. The electrostatic force FE is composed of 3 components: electric field force FEF, dielectrophoretic force FD, and image force FI, i.e., FE = FEF + FD + FI. The expression for FEF can be given by E0 with x = 0, y = 0, z = d + Rp multiplying the free charge Qp carried by the particle. FD is expressed using dyadic tensor notation. The multipole image force FI that acts on the induced multipole moments can be mathematically expressed considering the distance between the source point and the field point.
Then, the model of adhesive–elastic–plastic collision is demonstrated. In the present study, although lunar dust particles have extremely small size, irregular shape, and high hardness, they can be equivalently simplified to a spherical particle according to the conservation of normal contact force. The spacecraft coating consists of a Kapton layer. According to a dimensionless discriminant parameter μT, the commonly acknowledged JKR model which is useful for the analysis of collisions involving soft materials characterized by high interface energy can be utilized to describe the adhesive behavior of dust particles in this study. Additionally, in the context of low-velocity collisions, it is crucial to consider the energy dissipation caused by the plastic deformation of the coating. Based on the Thornton’s adhesive–elastic–plastic model, in which the adhesive energy dissipation is described by the JKR model, the process of low-speed collision can be divided into 3 distinct stages: the adhesive–elastic loading stage, the adhesive–elastic–plastic loading stage, and the adhesive–elastic unloading stage. Figure 3 depicts the distribution of contact stress between the dust and coating, referred to as p(r), throughout the various stages. In the adhesive–elastic loading stage (see Fig. 3A), the relationship between the JKR pressure distribution p(r), the relative compression δ, and the contact force P1 in the first stage can be mathematically expressed as
As illustrated in Fig. 3B, during the adhesive–elastic–plastic loading stage, the normal contact force P2 is formulated and simplified as
In the unloading stage (see Fig. 3C), the correlation between the contact force P3 and the contact radius a continues to closely adhere to the JKR model with an irrecoverable displacement δp:
Finally, results and discussion are presented. As for electrostatic force, that a dielectric coating with a high thickness and low permittivity can effectively reduce the electrostatic force between charged dust and spacecraft can be inferred from the variation in the electrostatic force FE between the charged particle and the coated ground plane. Figure 5 illustrates the variation in the theoretical and simulated electrostatic force between the charged particle and the coated ground plane, considering various important parameters of the particle. It can be summarized that for dimensionless distance d/Rp ≥ 1 the electrostatic force between a charged particle and a coated ground plane can be approximated as F ≈ K Rp2 σp2 / (1 + d/Rp)2. Besides, results also show that the surface charge density plays a more significant role than the spacecraft potential. In the context of low-velocity collisions, a larger size of particle results in a higher maximum coefficient of restitution. The adhesive van der Waals force rather than electrostatic attraction force predominantly influences the adhesion of lunar dust during the low-velocity collision process, if the surface charge density σp is below 0.1 mC/m2. It can be inferred that the low-interface-energy coating, which can be created by employing low-surface-energy material and increasing the surface roughness, is effective to decrease the difficulty of dust removal. When it comes to the interaction between low-velocity charged particle and spacecraft, it is important to acknowledge that the final adhesion of particles to the spacecraft is not solely determined by the initial collision. Adhesion to the surface occurs only when the initial velocity of a negatively charged particle is within the range of the critical adhesion and escape velocities. At last, the conclusion is drawn that the theory presented in this study offers a framework for investigating various issues pertaining to the accumulation of charged dust particles. It can be applied to analyze phenomena such as dust deposition in electrostatic precipitators and the adhesion of energetic powder to mixer walls and serves as a basis for predicting and mitigating dust adhesion. Future research will focus on the integration of irregular shapes of dust, the plasma environment, and solar radiation effect into the interaction model.
DOI
Fig. 2. Geometric representation of a charged dust particle positioned above a spacecraft surface with a coating layer.
Fig. 3. Schematic representation of particle-coating collision. (A) Adhesive–elastic loading stage, (B) adhesive–elastic–plastic loading stage, and (C) adhesive–elastic unloading stage.
Fig. 5. Electrostatic force FE expressed as a function of 3 variables: (A) the dimensionless separation distance d/Rp, (B) the particle radius Rp, and (C) the surface charge density σp. The theoretical results are represented by solid lines, and the simulated values are represented by dots.
Credit
Space: Science & Technology
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