Asteroid Torifun and Exoplanet Beta Pictoris Featured in Astronomical Images of the Week

The object that astronomers have been observing since 1998 surprised the scientific community by demonstrating signs of cometary activity. Initially classified as an asteroid, 1998 SH2 has been identified as a rare 'dark comet.'

Trajectory Change and Mystery

The study showed that some bodies in the Solar System can conceal hard-to-detect characteristics. Typically, comets reveal their presence through a coma and tails formed when sunlight heats the ice on the surface. Gas emission can also act as a small impulse, altering orbits.

So-called 'dark comets' follow a different path: they look like asteroids because they lack visible signs, but they exhibit movement changes similar to those caused by cometary activity.

Data Analysis and Activity Confirmation

A study published in Nature Astronomy analyzed 1998 SH2, which was observed for nearly three decades. In August 2025, as it approached Earth, the object was in a position different from what models based solely on gravity predicted. At the end of the same month, the Vikrota Observatory, part of the Southern Observatory for Near-Earth Asteroid Studies Wykrota-Centro de Estudos Astronômicos de Minas Gerais, located in Serra da Piedade, re-detected the body.

Calculations showed that the object was 19 standard deviations away from its expected position. For scientists, this discrepancy indicated additional acceleration, likely caused by gas ejection.

Visual Evidence of Hidden Comet

After detecting the trajectory change, the team studied deep images obtained by telescopes in Chile and Hawaii. These recordings captured a faint coma and a narrow tail over 20 arcseconds long. This was the first direct confirmation of cometary activity predicted based on this type of orbital change.

According to the study, dust ejection occurred continuously from late August to September 2025, indicating a process of sublimation—the transition of ice directly from a solid to a gaseous state. Key findings include: 1998 SH2 was previously classified as an asteroid; the body demonstrated acceleration unexplained by gravity; images confirmed the presence of a coma and tail; and this research may help in identifying other dark comets.

Significance for Planetary Defense

Scientists emphasize that 1998 SH2 does not pose an impact threat to Earth in the near future. Nevertheless, the existence of such objects could influence calculations in the field of planetary defense. Identifying these bodies is also important because an object considered an asteroid might possess cometary characteristics, changing assessments of its composition and potential deflection strategies.

Furthermore, the research suggests that an ancient population of dark comets may have contributed to the delivery of water to Earth during the planet's formation. The work published in Nature Astronomy expands knowledge about small bodies in the Solar System and shows that long-term observations can yield unexpected discoveries.

The Olhar Espacial program displays two notable astronomical images from the previous week every Friday. In the most recent edition, distinct representations of the Moon and a famous nebula were presented.

The Mineral Moon Image

The first image portrays the Moon in a waning crescent phase, but with an atypical appearance. Although it is common to observe the Moon in shades of gray through telescopes or photographs, this image uses advanced post-processing techniques to reveal subtle differences in color tones. These variations serve to illustrate the diverse chemical compositions present on the lunar surface.

Areas showing a bluish coloration indicate a higher concentration of titanium, while orange tones signal the existence of iron oxide-rich minerals. Due to the way this photograph highlights the composition of the lunar soil, it is often referred to as the 'Mineral Moon.'

The Pillars of Creation

The second image is a spectacular record of the famous formation known as the 'Pillars of Creation.' This cosmic structure is located in the center of the Eagle Nebula, approximately seven thousand light-years away, in the direction of the Serpent constellation. The pillars are composed of columns of molecular clouds that have been eroded by the action of young and hot stars.

It is an area characterized by an intense star formation process. It was this fact that led to the structure being named the 'Pillars of Creation' when photographed by the Hubble Space Telescope in 1995, making it one of the most emblematic images recorded by this instrument.