The solar system consists of a star called the “Sun” with “nine planets” rotating and revolving around it. The planets of our solar system are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. At the advanced level, the solar system includes the satellites of the planets; numerous comets, asteroids, meteoroids, and the interplanetary medium.
The Sun is the major source of electromagnetic energy (mostly in the form of heat and light) in the solar system. The Sun’s nearest known stellar neighbor is a red dwarf star called Proxima Centauri, at a distance of 4.3 light years away. A light year is a unit of astronomical distance equivalent to the distance that light travels in one year, equivalent to 6 trillion miles or 9.6 trillion km.
The whole solar system, together with the local stars visible on a clear night, orbits the center of our home galaxy, a spiral disk of 200 billion stars we call the Milky Way. The Milky Way has two small galaxies orbiting it nearby, which are visible from the southern hemisphere. They are called the Large Magellanic Cloud and the Small Magellanic Cloud. The nearest large galaxy is the Andromeda Galaxy. It is a spiral galaxy like the Milky Way but is 4 times as massive and is 2 million light-years away.
Our galaxy, one of the billions of galaxies known, is traveling through intergalactic space. The planets, most of the satellites of the planets, and the asteroids revolve around the Sun in the same direction, in nearly circular orbits. When looking down from above the Sun’s the North Pole, the planets orbit in a counter-clockwise direction. The planets orbit the Sun in or near the same plane called the ecliptic. Pluto is a special case in that its orbit is the most highly inclined (18 degrees) and the most highly elliptical of all the planets.
Because of this, for part of its orbit, Pluto is closer to the Sun than Neptune. The axis of rotation for most of the planets is nearly perpendicular to the ecliptic. The exceptions are Uranus and Pluto, which are tipped on their sides. The mystery of this space science is certainly beyond human comprehension and definitely beyond scope of this column. Scientists, around the years, are working to uncover these mysteries but instead are discovering more mysteries, a case of “the more you look, the less you understand”. You cannot, but marvel at the supreme and perfect design of the cosmos.
Mercury, Venus, Earth, and Mars are the four innermost planets in the solar system. They are called terrestrial planets because of their compact, rocky surfaces. The planets, Venus, Earth, and Mars have significant atmospheres while Mercury has almost none. The other planets; Jupiter, Saturn, Uranus, and Neptune are called the Jovian (Jupiter-like) planets This is because they are all gigantic compared to our planet, Earth, and they have a gaseous nature like Jupiter’s. The Jovian planets are also referred to as the gas giants, although some or all of them might have small solid cores.
Over the past five decades, a myriad of space explorers has gone out of the Earth’s atmosphere discovered our planetary neighbors and their numerous satellites.
My article on “Apollo II: Marking 60 years of man’s terrestrial romance with space” published on 2nd September 2021 discussed the manned planetary mission to the moon, which were done successfully. The Apollo program of the United States landed people on the moon.
Six missions landed men on the Moon, beginning with Apollo 11 in July 1969. Apollo 13 was intended to land, but couldn’t due to a malfunction aboard the spacecraft. All nine manned missions returned safely to the Earth. Countries leading in spacecraft technologies are USA, Russia, China, Japan and India. While the USA focused on the manned Apollo program, the Soviet Union focused on unmanned missions that deployed rovers and returned samples to the Earth. Three rover missions were launched, of which two were successful, and eleven samples return flights were attempted with three successes. After recording successes on the moon mission, the next challenge taken by the astronomers is the “mission to mars”.
Mars is the next simple destination after the moon mission for scientific discovery and robotic and human exploration as we expand our presence into the solar system. Mars formation and evolution are comparable to that of earth; therefore scientific study of Mars can help us learn more about our own planet’s history and future. Already some of the observations on Mars show conditions suitable for life in its past. Future exploration might uncover evidences of the fundamental mysteries of human existence and galaxies. This why the man’s attention is focused on mars in the last 50 years.
As mentioned, mars is the fourth planet from the sun and the second-smallest planet in the Solar System, after Mercury. It is sometimes called the “Red Planet” because of the iron oxide prevalent on its surface, which gives it a reddish appearance. Mars as one of the terrestrial planets has a thin atmosphere, with surface features reminiscent both of the impact craters of the Moon and the valleys, deserts, and polar ice caps of Earth.
The rotational period and seasonal cycles of Mars are similar to those of Earth. Mars is the site of Olympus Mons, the largest volcano and second-highest Known Mountain in the Solar System. The smooth Borealis basin in the northern hemisphere covers 40% of the planet and may be a giant impact feature. Mars has two moons orbiting around it, Phobos and Deimos, they are small and of irregularly shaped. These could be captured asteroids, similar to 5261 Eureka, a Mars trojan.
Physically, Mars is approximately half the diameter of Earth and its surface area is only slightly less than the total area of Earth’s dry land. Mars is less dense than Earth, having about 15% of Earth’s volume and 11% of Earth’s mass, resulting in about 38% of Earth’s surface gravity. Studies have revealed that the red-orange appearance of the Martian surface is caused by iron (III) oxide.
The space station also advances our understanding of how the body changes in space and how to protect astronaut health. Is man’s mission to the Mars possible?
(To be continued next week)
The views expressed in this article are the author’s own and do not necessarily reflect the editorial policy of Sky Daily