blog:articles:general:martian_weird_spring
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| blog:articles:general:martian_weird_spring [2019/07/22 18:26] – [Southern Hemisphere] Phil Ide | blog:articles:general:martian_weird_spring [2019/08/07 15:17] – [Southern Hemisphere] Phil Ide | ||
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| - | To explain this, we need to understand everything that is contributing to the issue, so we can then draw some conclusions that fit the data. Yup, we're going to be doing some science. Don't panic though, this is low-level stuff and pretty easy. | + | To explain this, we need to understand everything that is contributing to the issue, so we can then draw some conclusions that fit the data. |
| ===== Identifying the Problem ===== | ===== Identifying the Problem ===== | ||
| First off, let's take a snapshot of the data received from the InSight lander on Mars, and present it in an easily digestible form. | First off, let's take a snapshot of the data received from the InSight lander on Mars, and present it in an easily digestible form. | ||
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| Mars is in red, Earth is blue, Venus is yellow and Mercury is white. | Mars is in red, Earth is blue, Venus is yellow and Mercury is white. | ||
| - | The equinoxes and solstices for each planet are marked as ve, ss, ae and ws. VE stands for Vernal Equinox and this is also known as the Spring Equinox. At the equator, the vernal equinox occurs when the sun is directly overhead and when this occurs after winter. During spring, the position of the sun in the sky migrates north, until the moment of the summer solstice, when the sun is at its lowest angle vis the horizon and most northerly position. After that, it begins climbing back until it is once again above the equator - this is the autumn equinox. Thereafter, it descends towards the horizon again, this time south of the equator, until it reaches the winter solstice. | + | The equinoxes and solstices for each planet are marked as ve, ss, ae and ws. VE stands for Vernal Equinox and this is also known as the Spring Equinox. At the equator, the vernal equinox occurs when the sun is directly overhead and when this occurs after winter. During spring, the position of the sun in the sky migrates north, until the moment of the summer solstice, when the sun is at its lowest angle vis the horizon and most northerly position. After that, it begins climbing back until it is once again above the equator - this is the autumn equinox. Thereafter, it descends towards the horizon again, this time south of the equator, until it reaches the winter solstice. |
| The angle of the sun is described as L< | The angle of the sun is described as L< | ||
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| Since Mars is further away from the sun, the circumference of its orbit is much greater, and also means that it is moving //slower// in that orbit than Earth. This gives Mars a year of approximately 686 days as observed from Earth. It has its own rotational period though, which is (on average) 39 minutes and 53 seconds longer, so from a Martian perspective, | Since Mars is further away from the sun, the circumference of its orbit is much greater, and also means that it is moving //slower// in that orbit than Earth. This gives Mars a year of approximately 686 days as observed from Earth. It has its own rotational period though, which is (on average) 39 minutes and 53 seconds longer, so from a Martian perspective, | ||
| - | You'll also notice from the orbits that Earth has a pretty much circular orbit. This results in the months all being approximately the same length. Mars though has a very elliptical orbit. A month on Mars is deemed to pass while the planet crosses 30° around the sun. Since the orbit is elliptical, and since orbital mechanics requires objects to move slower as they approach | + | You'll also notice from the orbits that Earth has a pretty much circular orbit. This results in the months all being approximately the same length. Mars though has a very elliptical orbit. A month on Mars is deemed to pass while the planet crosses 30° around the sun. Since the orbit is elliptical, and since orbital mechanics requires objects to move slower as they approach |
| - | The Martian spring occurs when Mars is moving away from the sun, and summer when it begins its journey back. This is why these seasons | + | The Martian spring occurs |
| ===== Spring ===== | ===== Spring ===== | ||
| - | InSight, as mentioned before, is just a few degrees north of the equator. Therefore, shortly after the vernal equinox, the sun is directly overhead. After that, the sun (at midday) is heading lower and lower in the sky to the north. This in itself is enough to cause a drop in temperature. Add to that the fact that Mars is moving further and further away from the sun, and you can begin to understand why it is getting colder. Mars will continue to move further away until it reaches | + | InSight, as mentioned before, is just a few degrees north of the equator. Therefore, shortly after the vernal equinox, the sun is directly overhead. After that, the sun (at midday) is heading lower and lower in the sky to the north. This in itself is enough to cause a drop in temperature. Add to that the fact that Mars is moving further and further away from the sun, and you can begin to understand why it is getting colder. Mars will continue to move further away until it reaches |
| Late spring and early summer bring long days and short nights. Long days allow the sun to heat the ground and the atmosphere, while the shorter nights don't have enough time to allow the temperatures to drop to the extent they will during the long winter nights. The inability of Mars to retain heat is displayed in the graph at the top of the article - nighttime temperatures drop eighty degrees centigrade. Shortening the night by two hours is sufficient to allow some heat to be conserved into the next day. | Late spring and early summer bring long days and short nights. Long days allow the sun to heat the ground and the atmosphere, while the shorter nights don't have enough time to allow the temperatures to drop to the extent they will during the long winter nights. The inability of Mars to retain heat is displayed in the graph at the top of the article - nighttime temperatures drop eighty degrees centigrade. Shortening the night by two hours is sufficient to allow some heat to be conserved into the next day. | ||
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| ===== Conclusion ===== | ===== Conclusion ===== | ||
| - | What we have deduced, from examining the data, is that a combination of the elevation and angle of the sun in the daytime sky and the distance from the sun are causing temperatures to fall as spring progresses. We can expect temperatures to climb as the planet passes through | + | What we have deduced, from examining the data, is that a combination of the elevation and angle of the sun in the daytime sky and the distance from the sun are causing temperatures to fall as spring progresses. We can expect temperatures to climb as the planet passes through |
| This means we can make some predictions about Autumn and Winter. These seasons will be short, but the sun is going to be very low in the sky and the nights long. The word //cold// springs to mind. | This means we can make some predictions about Autumn and Winter. These seasons will be short, but the sun is going to be very low in the sky and the nights long. The word //cold// springs to mind. | ||
| ===== Southern Hemisphere ===== | ===== Southern Hemisphere ===== | ||
| - | What does this mean for southern spring and summer seasons? Mars will be as close to the sun as it ever gets. According to the Kasting | + | What does this mean for southern spring and summer seasons? Mars will be as close to the sun as it ever gets. According to the Kasting |
| Satellite data has already shown that such temperatures occur. | Satellite data has already shown that such temperatures occur. | ||
| - | Hellas Planitia, an incredibly large and deep impact basin in the southern hemisphere, is so deep that air pressure in its lowest areas is sufficient to sustain liquid water. At the moment, nearly all our experiments we've sent to the Martian surface, have landed in the northern hemisphere. The Curiosity rover is an exception to this, but it is wandering around inside Gale Crater, just south of the equator and only a few hundred kilometres from InSight. It will be very interesting to get on-sight weather data from deeper in the southern hemisphere, which we'll surely do as our ability to land on much more [[: | + | Hellas Planitia, an incredibly large and deep impact basin in the southern hemisphere, is so deep that air pressure in its lowest areas is sufficient to sustain liquid water. At the moment nearly all our experiments we've sent to the Martian surface have landed in the northern hemisphere. The Curiosity rover is an exception to this, but it is wandering around inside Gale Crater, just south of the equator and only a few hundred kilometres from InSight. It will be very interesting to get on-sight weather data from deeper in the southern hemisphere, which we'll surely do as our ability to land on much more [[: |
| //images courtesy of [[https:// | //images courtesy of [[https:// | ||