Exo planets 1

Focus on astrobiology, particularly the exploration of exoplanets beyond our solar system.
Current module emphasizes exploration of our own solar system due to its accessibility.
Inner solar system terrestrial planets and icy moons of outer planets are prime targets in the search for life.
The search for extraterrestrial life is a small part of the vast possibilities available in the galaxy.

Our solar system resides in a small area of the Orion arm of the Milky Way, which measures approximately 100,000 light years across.
Astrobiologists speculate that life may exist in other solar systems in our galaxy or even in other galaxies.
Detection of exoplanets, which are defined as planets that orbit stars other than our sun, remains a relatively new field of science.

The first exoplanet was discovered in 1992 orbiting a pulsar, an unexpected location.
Since then, there has been an exponential increase in confirmed exoplanets due to advancements in specialized space missions.
As of September, over 5,700 exoplanets have been confirmed, with nearly 5,000 additional candidates awaiting confirmation.
Many discovered exoplanets differ significantly from those observed in our solar system, leading to a broader understanding of planetary formation and behavior.

A key focus in astrobiology is identifying exoplanets located within the habitable zone, where conditions may support liquid water.
The habitable zone depends on the type and size of the host star, as different stars emit varying amounts of heat and light.
The concept of habitable zone is simplified; for example, Mars is in the habitable zone but does not support liquid water today.

Astronomers create catalogs of possibly habitable exoplanets and conduct follow-up observations to investigate their potential for hosting life.
Upcoming lectures will focus on methods to detect and study these candidates.

The Radial Velocity technique relies on the Doppler effect to measure the slight movement of a star influenced by an orbiting planet.
The center of mass between the star and the planet affects the star’s observed motion (wobble).
Enables the calculation of the planet's mass and orbit, depending on the size of the exoplanet and its distance from the star.
- Works effectively for larger planets and shorter orbits but struggles with Earth-sized planets due to minimal impact.

The Transit technique relies on detecting a star's brightness drop when a planet transits in front of it.
Larger planets cause more significant dips in brightness, allowing for estimates of size and distance from the star.
Secondary eclipses can provide insight into a planet's atmosphere by measuring thermal emissions and reflected light.

Projections about planetary systems are complicated by the fact that only about 10% of systems are aligned to be detectable via these methods.
Both methods can yield false positives, attributed to errors in light measurements or the influence of binary star systems.
Complexities arise when multiple planets in a system influence each other’s readings, requiring careful calculations and additional measurements.

The presence of various elements in a planet's atmosphere can indicate potential habitability, and current missions are starting to provide data on exoplanet atmospheres.
Specific elements are only produced by biological processes, highlighting the potential for life if detected in spectra.

The exploration of exoplanets is an exciting venture in astrobiology, with the number of confirmed exoplanets rapidly increasing.
Combining different detection methods allows scientists to infer essential characteristics such as planetary mass, radius, density, and atmospheric composition, thereby enhancing our understanding of these distant worlds.