Cosmic Spectacles: Exploring Extra-terrestrial Auroras

The beauty and wonder of auroras have captivated humanity for centuries, with Earth's mesmerizing displays of shimmering lights dancing across the night sky. However, beyond our own planet lies universe of celestial phenomena, including auroras in other planets. So, let’s explore the captivating auroras found on Extra-terrestrial planets of our solar system, shedding light on their unique characteristics and into the diversity of our cosmic neighborhood.

 

Image credit - NASA

King of auroras - Jupiter, the largest planet in our solar system, boasts some of the most awe-inspiring auroras ever observed. Its magnetic field interacts with electrically charged particles from its moon Io and the solar wind to create powerful and dynamic displays. The auroras on Jupiter are so immense that they can span an area larger than the Earth itself, with ultraviolet and infrared observations revealing complex patterns and structures. These phenomena show the sheer power of Jupiter's magnetosphere and its ability to generate mesmerizing light shows.

 

 

Image credit - NASA

 

Serenade of Colors - Saturn, famous for its mesmerizing rings, also possesses its own unique auroras. Unlike Jupiter's auroras, which primarily emit ultraviolet light, Saturn's auroras emit a variety of colors, including infrared, ultraviolet, and visible light. Scientists believe that Saturn's auroras are caused by its interaction with charged particles originating from the Sun, similar to Earth's auroras. These colorful displays add to the otherworldly charm of the ringed planet, painting the night sky with ethereal hues.

 

 

 

 

Ice Giants with Subtle Lights - Uranus and Neptune, known as the ice giants, are lesser-known but equally fascinating worlds that possess their own auroras. These icy planets have a distinct composition and magnetic field, leading to unique auroral phenomena. Due to their extreme axial tilts, the auroras on Uranus and Neptune are unusual in that they appear as subtle, faint glows. Observations from spacecraft missions, Voyager 2 have revealed intermittent bursts of auroras on Uranus and Neptune.

Image credit - NASA's Goddard Space Flight Center/Jenny Hottle

A Hint of Auroral Magic - While not as pronounced as those on Jupiter or Saturn, Mars also experiences its own version of auroras. Unlike the other planets mentioned, Mars does not possess a global magnetic field. However, localized magnetic fields are found in specific regions of its crust. During intense solar activity, these magnetic fields can interact with the solar wind, generating faint auroral glows near the planet's surface. Although the Martian auroras may be elusive, they serve as a reminder of the dynamic interplay between a planet's magnetic field and its surrounding environment. 

Animation showing proton aurora at Mars. Credits: NASA/MAVEN/Goddard Space Flight Center/Dan Gallagher

 

Auroras occurs not only on Earth but also across our cosmic neighborhood. From the colossal displays on Jupiter and the multicolored symphonies on Saturn, to the subtle glows on Uranus and Neptune, each planet's auroras offer a glimpse into the unique characteristics of their magnetospheres. As we continue to explore the wonders of our solar system, these extraterrestrial auroras serve as a reminder of the vast diversity and awe-inspiring beauty that lies beyond our home planet.

How do green spaces lower temperature in cities?

Green space or the open natural environments in the cities are the lungs of the cities. It can be in the form of  public parks or private campuses and community/institutional parks/gardens. State and national parks or open country spaces on the periphery are not urban green spaces as their benefits for the city are limited.

The benefits of urban green spaces are unlimited. Man's bond with nature is ancient. Nature is a source of inspiration and relaxation for humanity. People living in stressed, congested city environments often long for the countryside natural environment. The individuals and communities near green spaces receive valuable positive benefits, which may be in the form of pure air, better physical or mental health, recreation and much more. However, these benefits are not only limited for humans but the city environment also benefits from these green spaces.

Role of green spaces in reducing the temperature of the cities is widely accepted. Concrete city structures get heated up quickly during day time and release heat during night. Due to this, the average temperature in cities can be 1-3 degrees celsius higher than in the surrounding rural regions. This results in the formation of  Urban Heat Islands, or UHIs. If we try to visualize the temperature profile of urban and surrounding rural regions graphically and spatially, it will show an island of higher temperature than surroundings. Thus it is named as urban heat islands. The concrete structures in the cities are mainly responsible for the heat island effect. The pollution from the automobile and industry releases carbon dioxide. CO2 is a known greenhouse gas which increases temperature of the cities.

Green spaces within urban areas can restrict the direct heating of the concrete pavements. The tree canopy reduces the incoming solar radiation through shading.  The process of evapotranspiration reduces heat by releasing water into the air. Some factors like type of  green space (park or nature reserve), type of plant species, and the density of vegetation also plays an important role. For instance, trees with broad canopy like banyan or peepal trees, provide shade in a larger area and are more effective in reducing heat. Thus, green spaces decrease the overall effect of UHIs. The larger the green spaces in the city, the smaller will be the heated areas. Clustered green spaces are more effective in reducing temperature. Green spaces are also helpful in reducing pollution by absorbing carbon dioxide and releasing oxygen. This green space works in many ways in reducing the temperature of the cities.