Seasons are caused by the inclination of a planet's rotational axis relative to the plane of its orbit around the sun. Earth's axis is inclined 23.5 degrees. On the first day of summer in the northern hemisphere, Earth's north pole is tilted 23.5 degrees toward the sun, so the northern hemisphere receives more sunlight. Half a year later, on the first day of winter, Earth's north pole is tilted away from the sun, so the northern hemisphere receives less sunlight.

Essentially, an analemma is the pattern the sun makes in the sky if you plot its position at noon every day in the course of a year. If one had a sextant, a chronometer set to the time and date on the prime meridian, and an analemma chart, one could determine one's position with fairly good accuracy. The shape of the analemma is influenced by the magnitude and phasing of two factors: axial inclination and orbital eccentricity. See similar questions...

Finding life on Mars would excite researchers for a variety of reasons. Firstly, it would just be interesting to know that life did (or does) exist elsewhere in the universe. Humans have been wondering about this question almost as long as we have been in existence. Finding evidence that suggests that we may not be alone, that Earth is not the only planet capable of sustaining life, would be an amazing revelation. As for scientists, many want to know how and why life was created on Earth. See similar questions...

The information in a Mars document is organized similar to a PDF document. Mars represents document information by combining standard XML, images, fonts, and color formats within a Zip-based package. Page content is represented in SVG. In Mars, the pages, images, fonts, bookmarks, and other document components appear as separate files within the Zip package. The Mars components such as bookmarks are easier to manipulate by virtue of their XML representation. See similar questions...

Orbiter now includes Duncan Sharpe's TransX MFD mode, which is a great tool for setting up interplanetary routes. You need to activate the TransX module in the Orbiter Launchpad dialog to use this. TransX is quite a complex navigation tool, so to understand the concept and options, make sure you read the TransX manual (in the Doc folder) carefully. See similar questions...

Mars and Earth are like two cars on a racetrack as they journey around the Sun. Earth is on the inside track and travels faster than Mars, which is on the outside. When Earth laps Mars about every two years, it comes as close as 35 million miles (56 million km) or as far away as 63 million miles (101 million km) because of Mars’ highly elongated orbit. See similar questions...

For two reasons, an Earth calendar will not work on Mars. First of all, a Martian sol is nearly forty minutes longer than an Earth day. This may not seem like much, but over the course of a month this difference accumulates to nearly an entire day. So if one tried to use an Earth calendar on Mars, the months that contain 31 days on Earth would generally have only 30 sols on Mars, and most of our 30-day months would be only 29 sols long on Mars. See similar questions...

Many Martian calendars divide the year into nearly equal lengths of time (to within a sol). A few instead divide the orbit of Mars around the sun into equal arcs, and since Mars travels at different speeds at different points in its elliptical orbit, the months on such calendars vary in their duration by about 50 percent. Although each season contains the same number of months on such calendars, each month has a different number of days from every other month. See similar questions...

NASA has explored the moon using robotic spacecraft, and we plan to continue to use robotic spacecraft to collect lunar data enabling human scientists to return to its surface. Science is just one reason for returning humans to the moon. The primary reason is that the moon provides opportunities to develop technologies and techniques needed for opening the space frontier. It allows us to learn how to survive long term stays on other worlds while only three days travel time from Earth. See similar questions...

The sample return capsule, still attached to the main Genesis spacecraft, will be aligned to its proper entry orientation about six hours before entry. At that time it will be spun to 15 revolutions per minute, adding stability for its descent into Earth's atmosphere. The capsule will be released two hours later. After the capsule is released, the main spacecraft will be diverted so it cannot collide with the sample return capsule. See similar questions...

The amount of time it takes to transmit a signal from Mars to Earth or from Earth to Mars using the High Gain Antenna varies according to the relative positions of Earth and Mars in their orbits around the sun. At the time of the July 4th landing, it took approximately 10 minutes to transmit a signal. See similar questions...

Late March through late May represents the period of long rains in Tanzania. This is usually not an ideal time to plan a safari because of the potential for sudden downpours. Directly after the long rains, however, is a wonderful time to visit Tanzania's national parks due to the abundance of wildflowers and vegetation. It is also a wonderful time to go on safari because the level of dust and the number of tourists is minimal. See similar questions...

The Spiders From Mars were David Bowie/Ziggy Stardust's three-piece rock band from 1971 to mid 1973, however they were only officially known by this name following the album's release in June 1972. Bowie has said that the inspiration for the name came when he was writing the song "Ziggy Stardust". The band consisted of: quot;It was Ziggy Stardust and the Spiders from Mars and somehow, along the lines, the Spiders got attached to David Bowie. See similar questions...

This is very unlikely. All US space missions are required to meet planetary protection standards, and these standards are particularly stringent for Mars. As a Mars lander with no life detection experiments, the Mars Polar Lander is categorized as a Category IV A mission. This requires that the spacecraft has to be assembled in a class 100,000 clean room, and that contamination control effectiveness must be monitored and demonstrated by periodic microbiological assays. See similar questions...

Several ideas have been put forth regarding Martian clocks. Since a Martian sol is only three percent longer than an Earth day, the most straightforward approach is to simply stretch Earth's units of time into slightly longer hours, minutes, and seconds (this system is used by NASA and JPL). Another approach is to add 39 minutes, 35.2 seconds at the end of 24 hours. Still another idea is to have a "metric" clock based on powers of ten. See similar questions...

Mars documents, like PDF documents, can be displayed within a viewer application. When viewed, Mars documents have similar appearance and behavior as a PDF document with similar content. Other than having a different file suffix, an end user would not see any difference between a Mars document and a PDF document. However, if you look under the hood, a document created in the Mars format will appear different, containing XML components that enable some exciting enterprise use cases. See similar questions...

the core of Earth Force activites are annual campaigns on specific environmental topics chosen by youth. Campaign materials, including student guides and teacher guides will be broadly distributed free of charge through numerous channels. Earth Force is also currently developing a series of action kits for youth. Action kits are designed to provide in-depth action learning for youth interested in exploring specific environmental topics in greater depth. See similar questions...

The heat from the earth's core continuously flows outward. It transfers (conducts) to the surrounding layer of rock, the mantle. When temperatures and pressures become high enough, some mantle rock melts, becoming magma. Then, because it is lighter (less dense) than the surrounding rock, the magma rises (convects), moving slowly up toward the earth's crust, carrying the heat from below. Sometimes the hot magma reaches all the way to the surface, where we know it as lava. See similar questions...

Some have vessels (Servitors of David and Laurence, for example). Those who aren't that lucky arrive in celestial form unless they have some method of viewing the Earth so they can use their resonance at a distance. See similar questions...

While Florida definitely has seasons, the weather isn't as pronounced as in the northern U.S. states and Canada. From a vacation point of view, Florida's four seasons are: Spring: This popular vacation time has mild weather. While major attractions are less crowded and some hotels offer discounts, humidity can be unbearable in April, and many avoid this season because of spring breakers. Summer: Sizzling hot and humid, sudden and sporadic thunderstorms cool things off a little. See similar questions...