Many people are attracted to diamonds. It's not
because diamonds are the hardest substance that everyone has become a fan of
hardness. Natural diamonds are rare, which is why they are so expensive. In
Bangladesh, the price of one gram of diamond is over four lakh takas. But what
if diamonds were constantly raining down from the sky like raindrops, scattered
everywhere? That would be unbelievable, or at most, a fantasy. But what if I
told you that this is happening on one of the planets in our solar system!
Similarly, if someone says that the sun rises in the west, we will naturally
think the person is mistaken. But the truth is, the sun does rise in the west
on one of the planets in our solar system. On some planets, a day is longer
than a year. Sounds astonishing, doesn't it? There are countless astonishing
phenomena occurring on the planets and moons of our humble sun. Today, we will
discuss a few of these amazing phenomena.
The Sun and Its Family
If our solar system were a family, the head of that
family would be the Sun. Its children, the planets, revolve around it. However,
calling the planets the Sun's children can be misleading because each of the
Sun's planets is as old as the Sun itself—4.5 billion years. Not only that, but
the moons orbiting the planets also originated at the same time, making them as
old as the Sun too. In this solar family, the father, son, and grandson all
share the same age.
So, how many members are there in this family? There
are eight planets and a total of 288 moons. In addition, there are dwarf
planets, which have eleven moons of their own. As satellite technology
advances, new discoveries are continuously increasing the number of solar
system members. Despite being the head of such a large family, the Sun is not
one of the brightest stars in the universe.
Among the hundreds of billions of stars in the
universe, our Sun is a very ordinary G-type star located about 150 million
kilometres from Earth. The temperature of a G-type star is about 6,000 degrees
Celsius, which gives it its yellow colour. To summarize the size of the Sun: its
diameter is 1,390,000 kilometres, which is 108 times that of Earth. This means
that to stretch from one end of the Sun to the other, you would need to line up
108 Earths side by side. The volume of the Sun is so vast that 1.2 million
Earths could fit inside it. If you combine everything in the solar system
except the Sun, the Sun itself is still 750 times larger. The Sun is 333,000
times heavier than Earth, containing 98% of the mass of the entire solar
system.
Humans have been observing the Sun since they
developed intelligence, which is where the journey of astronomy began. However,
even after all these years, many aspects of the Sun remain equally astonishing.
For example, the Sun's temperature.
The Temperature of the Sun's Atmosphere is Higher Than
Its Surface Temperature
The Sun has many layers of gas inside it. Although
there are no clear boundaries between these layers, each one has a distinct
function. The Sun is primarily divided into two parts: the inner part and the
outer part. The inner part can be divided into three regions. At the very
center is the core. Surrounding the core is the radiative zone. Encircling the
radiative zone is the convection zone. The outer part consists of three layers
of gas, collectively referred to as the Sun's atmosphere. The innermost layer
of this part is the photosphere, which surrounds the convection zone.
Encircling the photosphere is the chromosphere. The outermost layer is the
corona, which is the Sun’s outer surface.
The core of the Sun is the hottest part, with a
temperature of about 15 million degrees Celsius. It occupies about a quarter of
the Sun’s volume but holds almost half of its mass due to the dense, hot gas.
The core is the source of all the Sun's energy, where nuclear fusion occurs.
Every second, four million tons of hydrogen are converted into energy in the
Sun's core.
The next layer outside the core is the radiative zone,
filled with gamma rays. This region accounts for about a third of the Sun's
volume, with temperatures around 5 million degrees Celsius. The energy produced
in the core passes through this region in the form of electromagnetic waves.
Due to interactions with dense gas, the energy flow here is extremely slow,
taking between 30,000 and 100,000 years to move through this zone. Gamma rays
are gradually transformed into visible light with longer wavelengths as they
move through this region. Once this energy leaves the radiative zone, it takes
just 8 minutes and 26 seconds to reach Earth.
Beyond the radiative zone is the convection zone,
where the temperature averages around 5,500 degrees Celsius. This zone occupies
more than 50% of the Sun's volume. Energy is transported through this zone by
the convection of plasma, similar to how hot water rises and cold water sinks
in a boiling pot. Energy moves quickly through this region, taking about a week
to reach the photosphere.
Since the Sun is not a solid object but a gas giant,
it has no solid surface. The "surface" is a 500-kilometer-thick layer
of gas called the photosphere, which is what we see when we look at the Sun.
Energy from the photosphere is emitted into space as light. The photosphere is
very transparent, allowing energy to spread out as heat and light. When we look
at the Sun, it appears to be a glowing ball of gas because we can see the
convection zone through the photosphere.
Starting from the photosphere is the Sun's atmosphere.
The layer immediately above the photosphere is the chromosphere, the innermost
layer of the Sun's atmosphere, visible only during a total solar eclipse. The
chromosphere's temperature is about 11,000 degrees Celsius. While the Sun's
surface temperature is around 5,500 degrees Celsius, the temperature jumps to
11,000 degrees Celsius just 5,000 kilometres above the surface. The surprises
don't end there. Moving outward to the corona, the outermost layer of the
atmosphere, the temperature skyrockets to about 1.7 million degrees Celsius.
What causes this?
Scientists have proposed some hypotheses, but the
exact reasons are still unknown. One theory is that plasma moving from the
photosphere to the chromosphere increases the temperature. From there, it moves
to the outermost layer, raising the temperature by several hundred thousand
degrees. Another theory is that the strong magnetic fields in the Sun's
atmosphere increase the temperature. It is hoped that the satellite 'Parker,'
sent close to the Sun, will help provide accurate explanations for many of the
Sun's mysteries.
