HD 189733 b

There is a deep blue planet far away.

It orbits a bright star.

This world is very big. It is even bigger than Jupiter. It is also very hot.

The weather there is wild. It rains molten glass! The planet also has very dry air.

Scientists use big tools to see it. They found water vapor in the air. They also found gas called carbon dioxide.

This planet moves very fast. It circles its star in just two days. It is a truly amazing place.

HD 189733 b is a far-off planet. It orbits a star in the Vulpecula constellation.

This world is a hot Jupiter. That means it is a big, hot gas planet. It is even larger than Jupiter. It is also heavier than Jupiter.

This planet has a deep blue color. Scientists found this by looking at its light. The weather there is very wild. It can rain molten glass! The air is also very dry.

Researchers use many tools to study it. They used the Spitzer Space Telescope to make a heat map. This map shows how hot different parts are. They also found many things in the air. They found water vapor and carbon dioxide. They even found methane and sodium.

Some of the planet's air is even evaporating. This means the gas is floating away into space. The planet moves very fast. It circles its star every 2.2 days.

HD 189733 b is a fascinating planet far away from our Solar System. It lives in the constellation known as Vulpecula. This world is what scientists call a "hot Jupiter." This means it is a huge gas planet that stays very hot.

It is actually 11.4% larger in radius than Jupiter. It is also 11.2% heavier than that giant planet. Because it is so close to its star, it orbits very quickly. It completes one full trip around its star every 2.2 days.

Learning how this planet works involves looking at its amazing atmosphere. The planet has a deep blue color because of something called Rayleigh scattering. This happens when light hits the air in a certain way. The weather there sounds like something from a scary story. Scientists believe it might rain molten glass! This happens because of particles like magnesium silicate in the air. The planet is also very dry. In 2014, NASA announced that this planet has a very dry atmosphere.

Astronomers have been studying this world for a long time. A team in France first discovered the planet on October 5, 2005. They found it by watching it pass in front of its star. This is called a transit. Later, in 2006, a team led by Drake Deming found heat coming from the planet. In 2007, Carl Grillmair led studies using the Spitzer Space Telescope. These scientists used many different tools to learn about the planet. They used telescopes on the ground and even telescopes in space.

There are many specific facts that make this planet special. It is the first exoplanet to have a thermal map made. A thermal map shows how heat is spread across the surface.

Scientists also found carbon dioxide and water vapor in the air. They even found sodium, potassium, and methane. In 2024, researchers detected hydrogen sulfide in the atmosphere. The planet is also losing its air to space. It evaporates at a rate of 1 to 100 gigagrams every second.

This planet helps us understand other worlds in the universe. It was the first planet to have its color determined by two different methods. It was also the first to have its transit viewed in X-rays.

We can compare its fast orbit to a spinning top. Most hot Jupiters are "tidally locked" to their stars. This means one side always faces the star and stays in permanent daylight. The other side always faces away and stays in permanent night. This makes the planet a very extreme place to visit.

HD 189733 b is a massive exoplanet located in the constellation Vulpecula. Astronomers classify this world as a "hot Jupiter." This term describes a gas giant that orbits very close to its host star.

Because of its proximity to the star, the planet is extremely hot. It has a mass 11.2% higher than Jupiter. Its radius is also 11.4% larger than Jupiter's. This planet is a key subject for scientists studying distant worlds. It is the closest transiting hot Jupiter to Earth.

Scientists discovered this planet on October 5, 2005. A team of astronomers in France found it by observing a transit. A transit occurs when a planet passes in front of its star. This movement causes a small dip in the star's light. Astronomers also used Doppler spectroscopy to detect the planet. This method involves measuring the "wobble" in the star's motion. The planet's high mass causes the star to move with a semi-amplitude of 205 m/s. This orbital motion helps scientists calculate the planet's characteristics. The planet completes one full orbit every 2.2 days.

Understanding the atmosphere of HD 189733 b requires complex instruments. Researchers use high-resolution tools from both Earth and space. In 2006, Drake Deming's team detected infrared thermal emission. They did this by measuring the flux decrement during a secondary eclipse. A secondary eclipse happens when the planet passes behind its star. In 2007, Carl Grillmair led spectroscopic observations using the Spitzer Space Telescope. These studies helped create the first thermal map of an exoplanet. This map shows how heat is distributed across the planet. The temperature range is between 973 K and 1,212 K.

The planet has a very distinct appearance and strange weather. It has a deep cobalt blue color. This color likely comes from Rayleigh scattering. Rayleigh scattering happens when light interacts with particles in the atmosphere. In the atmosphere, scientists found magnesium silicate particles. These particles are very small, between 10⁻² and 10⁻¹ micrometers. This leads to a very violent weather pattern. Researchers believe it may rain molten glass on this world.

The atmosphere is also described as being very dry. This was announced by NASA in July 2014.

Detailed chemical analysis has revealed many substances in the air. HD 189733 b was the first exoplanet to have carbon dioxide confirmed. Scientists also found water vapor and neutral oxygen. Other compounds like methane and carbon monoxide have been detected. In 2020, potassium was identified in the atmosphere. In 2024, researchers detected hydrogen sulfide. Sodium has also been observed at high concentrations. The presence of these chemicals helps scientists understand planetary evolution. For example, the high temperatures should cause water and methane to react. This reaction would normally replace the atmosphere with carbon monoxide.

The planet is also physically changing over time. Observations using HI Lyman-alpha show that the planet is evaporating. It loses its atmosphere at a rate of 1 to 100 gigagrams per second. This happens because the planet is losing atomic hydrogen to space.

This makes it the second planet where atmospheric evaporation has been detected. Most hot Jupiters are also tidally locked to their stars. This means one side faces the star in permanent day. The other side faces away in permanent night. This creates massive winds up to 2 kilometers per second. These winds blow from the day side to the night side.

Studying HD 189733 b connects many different fields of science. It links astronomy with chemistry and meteorology. By studying its X-ray spectrum, scientists see how atmospheres block light. The planet blocks three times more X-rays than visible light. It also helps researchers understand star-planet interactions. While some thought the planet caused stellar flaring, newer data suggests otherwise. This shows how important it is to constantly test new theories. This planet remains one of the brightest and most studied targets in the sky.