Introduction and Monthly Reminders
March has been a mix of clear skies, rain storms, snow storms, wind, and just plain clouds. The temperatures have also fluctuated a bit, but overall it has been a decent month for stargazers to dust off their equipment and get back out under the stars. I have been able to enjoy a few quick nights of stargazing during the first half of March and hope to spend more time out as the weather clears.
March will still offer observers the chance to view a planetary conjunction between Venus and Saturn on the 21st. Observers may still also view the zodiacal light and comet Pons-Brooks from a dark sky location. The ideal date for attempting to view all 110 objects of the Messier Marathon has passed, but most of the objects can still be viewed during the remaining days of the month and into April.
Jupiter
Jupiter formed about 4.5 billion years ago with the rest of the solar system. Based on computer simulations, it is thought that this giant planet settled into its current orbit, about 5.2 Astronomical Units (AU) from the Sun about 4 billion years ago. This planet has earned its name from the Roman king of gods, Jupiter. Several of its moons are also named after mythological characters related to the Roman god or the Greek god, Zeus.
Like our Sun and other stars, Jupiter is mostly made up of hydrogen and helium. It also has ammonia, water, sulfur, and phosphorus in its atmosphere which create the different colored cloud bands. It is unclear if Jupiter has a solid core or is made up entirely of gas, but hopefully, future missions to this planet can answer this question. It is known, however, that the extreme pressure and temperature below the cloud tops are enough to crush, melt, and vaporize a spacecraft.
Jupiter is the largest planet in our solar system by a wide margin. In fact, this gas giant could fit two of all of the planets in our system inside and still have room to spare. If the Earth were the size of a grape, Jupiter would be about the size of a basketball. Jupiter is also large enough to be home to storms that are larger than other planets in the solar system. For example, the Great Red Spot is a storm that has been raging for hundreds of years and could fit at least two Earth-sized planets inside of it. Observations of the Great Red Spot have detected that this storm has been shrinking for the past century, and could have fit more than three Earth-sized planets inside.
Jupiter has a tremendous gravity field around it which can suck in smaller bodies. It currently has 95 known moons orbiting with the four largest, known as the Galilean Moons, which can be seen with a pair of binoculars. While Jupiter cannot support life as we know it, its moon, Europa, has a vast ocean beneath its icy crust which may be able to support life. There have been talks of future missions going to Europa, and other moons of Jupiter, to search for signs of life. Jupiter also has a ring system that was only detected 45 years ago by the Voyager 1 mission. The rings are made up of mostly dark particles and do not reflect very much light, making them hard to detect and nearly invisible to Earth-based observations.
The king of planets rotates about its axis quicker than any other planet in our solar system. It takes less than 10 hours for Jupiter to complete one full rotation. This is beneficial for Jupiter observers so they can view a large part of the surface in a single night when it is in opposition. Being further out from the Sun, Jupiter has a longer year than the inner planets since it has a greater distance to travel. It takes about 12 Earth-years to complete a single trip around the Sun.
I can recall an astronomy homework assignment that asked me to calculate the amount of sunlight reflected by Jupiter and compare it to the amount of light from observations. It turns out that Jupiter emits more light than it reflects, meaning that this planet produces its own light! Yes, my answer was correct! Due to the mass of Jupiter, it can produce energy through gravitational contraction. This energy is given off as light that can be detected through observations. It was once thought that Jupiter could have been a failed brown dwarf star, but studies have shown that it is not massive enough to achieve an internal temperature and pressure for nuclear fusion, the process required for a star to be born. A small brown dwarf is only about 15% larger than Jupiter but is also 80 times denser.
Pioneer 10 and Pioneer 11 were the first missions to fly by Jupiter in 1973. Pioneer 10 was designed for a 21-month mission but instead lasted until 2003. Pioneer 10 sent back the first images of Ganymede and continued to visit the outer solar system. In 2017, Pioneer 10 was about 120 AU from the Sun, heading towards the red star, Aldebaran. It should reach its destination in about two million years.
Voyager 1 and Voyager 2 also flew by Jupiter, sending back images of the giant planet and some of its moons. Voyager 1 was the first to spot volcanoes on Io. Galileo was sent to orbit Jupiter in 1989 and sent back new images and data, including the discovery of an ocean beneath Europa's icy crust. Galileo was sent deep into Jupiter's atmosphere in 2003, destroying the orbiter and protecting the possibility life on Europa.
Juno was launched in 2011 and is still orbiting Jupiter today. This mission is studying the atmosphere of Jupiter and trying to answer questions about how this giant planet formed so scientists can better understand other gas giants in the universe. The European Space Agency (ESA) also has a mission en route to Jupiter. Juice, the Jupiter Icy Moons Explorer, will study the different moons of Jupiter. It launched in April 2023 and is expected to arrive at Jupiter in 2031 after a few gravity-assist maneuvers from the Moon, Venus, and the Earth.
The next planned mission to Jupiter, the Europa Clipper, is expected to launch in 2030. As its name suggests, it will study Europa, an icy moon of Jupiter. Its intention is to see if the sub-surface ocean has the proper conditions to support life as we know it.
Check back soon for my next Monthly Night Sky Report!
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| Now get outside and look up! |
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