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Planet Walk

solar system

Welcome to the UAF Planet Walk!

Take an out-of-this-world stroll along the UAF Planet Walk! This 1:4.4 billion scale model of the solar system will take you on a little less than one mile walk through our solar system.

The Planet Walk begins at the west end of Yukon Drive, near the intersection with Koyukuk Drive. As you move east along Yukon Drive, nine signs represent the sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. A 10th sign highlights Pluto, which was reclassified as a dwarf planet in 2006. Each station presents an image of the planet and information about it.

The location of each sign is scaled to approximate the featured planet’s distance from the sun. The size comparison on the signs is 10 times larger than the distance scale in order to make Pluto visible on its sign; if the same scale were used for both the size and the distance comparisons then a visitor would have to walk almost 10 miles to see the whole installation!

Along the way, you might discover that the sunny side of Mercury is hotter than a pizza oven, or that there are clouds of sulfuric acid on Venus, or that the diameter of Pluto is roughly equivalent to the longest length of Alaska from top to bottom. Planning to land on Jupiter? Forget it – this planet is hot and gaseous, and has no solid surface.

UAF Geophysical Institute faculty and students have contributed to space missions exploring the solar system, including NASA’s New Horizons mission to Pluto and the Kuiper Belt. Students have many opportunities to participate in cutting-edge research at UAF, a Land, Sea and Space Grant university.

The UAF Planet Walk was developed by members of the Alaska chapter of the Society of Physics Students, a club associated with the College of Natural Science and Mathematics. A student artist from the College of Liberal Arts produced the design concept. The Planet Walk was sponsored by the Geophysical Institute.

Select from the planets below to learn more about them, or explore further online at https://solarsystem.nasa.gov/planets/overview/.

Source for graphic: NASA/Jet Propulsion Laboratory-Caltech. Artist's rendition of our solar system. Not to scale.

Sun
extreme ultraviolet image of the sun courtesy ESA/NASA/SOHO
extreme ultraviolet image of the sun courtesy ESA/NASA/SOHO

 

Facts about the sun:

The sun is a giant hot sphere of gas at the center of our solar system. Nuclear fusion is the source of the sun's energy. The sun is the main source of energy for sustaining life on Earth. 

The sun is constantly ejecting charged particles and plasma, carried by the  solar wind, which, in part, makes Earth's aurora possible. Auroras also occur on Mars, Jupiter, Saturn, Uranus, and Neptune.

Sun statistics:

  • Distance from Earth: 150 million km (93 million mi)

  • Diameter: 109 x Earth

  • Mass: 333,211 x Earth

  • Core is 27 million degrees F (15 million degrees C)

  • Time for one full rotation ("day"): 25.38 Earth days

  • Light takes about 8 minutes to reach Earth

Mercury
Mercury image courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
image courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

 

Facts about Mercury:

Mercury is covered by a massive network of fault lines that originated when the planet cooled, and shrank, shortly after it was formed. Water ice is believed to exist in craters near Mercury's poles, where it would be in constant shadow and never melt. 

Like our moon, Mercury is airless. Because of this, and how close it is to the sun, Mercury has the greatest day-night temperature difference of all the rocky planets (425˚C to -180˚C).

Mercury statistics:

  • Distance from the sun: 57 million km (35 million mi)

  • Diameter: 0.383 x Earth

  • Mass: 0.0553 x Earth

  • Time for one full orbit ("year"): 88 Earth days

  • Time for one full rotation ("day"): 4,222.6 Earth hours

  • Smallest and fastest moving planet in the solar system

Venus
Venus image © 2005 Mattias Malmer, NASA/JPL
image © 2005 Mattias Malmer, NASA/JPL

 

Facts about Venus:

Venus is the hottest planet in the solar system, with surface temperatures hot enough to melt lead, zinc, tin, and several other metals. It can reach temperatures of 462° C (864° F), about twice as hot as a typical household oven.

Extreme heat is trapped within Venus's atmosphere by a thick layer composed of carbon dioxide and clouds of sulfuric acid.

Venus has no moons and no rings.

Venus statistics:

  • Distance from the sun: 108 million km (67 million mi)

  • Diameter: 0.95 x Earth

  • Mass: 0.815 x Earth

  • Time for one full orbit ("year"): 225 Earth days

  • Time for one full rotation ("day"): 2,802 Earth hours

  • Rotates clockwise, the opposite of Earth

Earth
Earth image courtesy NOAA/NASA GOES
image courtesy NOAA/NASA GOES

 

Facts about Earth:

Earth houses more than 7.5 billion people and is the only planet known to support life. Earth’s atmosphere is composed mainly of nitrogen and oxygen. 

The rotation of the planet's liquid iron core generates a powerful magnetic field. This magnetic field funnels charged particles from the sun into Earth's atmosphere at both poles. The particles excite gases in the atmosphere, producing lights in the sky we know as aurora borealis and australis.

Earth statistics:

  • Distance from the sun: 150 million km (93 million mi)

  • Diameter: 12,756 km

  • Mass: 5,972,190,000,000,000,000,000,000 kg

  • Time for one full orbit ("year"): 365.2 days

  • Time for one full rotation ("day"): 24 hours

  • Water covers 71% of Earth's surface

Mars
Mars image courtesy NASA/ESA
image courtesy NASA/ESA

 

Facts about Mars:

Astronomers once believed Mars had seas and regions of vegetation. They now understand sandstorms cause the light and dark areas visible on the planet's surface.

Evidence of erosion caused by flowing water implies Mars was once much warmer and had a thicker atmosphere.

Mars has canyons and volcanoes, just like Earth. It cannot currently support life because of its thin atmosphere and limited amounts of oxygen and water vapor. 

Mars statistics:

  • Distance from the sun: 228 million km (142 million mi)

  • Diameter: 0.53 x Earth

  • Mass: 0.107 x Earth

  • Time for one full orbit ("year"): 1.88 Earth years

  • Time for one full rotation ("day"): 24.7 Earth hours

  • Elliptical, egg-shaped orbit and two moons

Jupiter
Jupiter image courtesy NASA/ESA/J. Nichols
image courtesy NASA/ESA/J. Nichols

 

Facts about Jupiter:

Jupiter is the largest planet in the solar system. It is a gas giant twice as massive as all the other planets combined.

The planet is believed to have 79 moons, 53 of which have been named. Jupiter has rings that are difficult to see, even with telescopes. The rings are composed of dark dust, possibly from its moons.  Jupiter's Great Red Spot is a hurricane-like storm that has been observed for more than 300 years.

Jupiter statistics:

  • Distance from the sun: 795 million km (494 million mi)

  • Diameter: 11.21 x Earth

  • Mass: 317.8 x Earth

  • Time for one full orbit ("year"): 11.9 Earth years

  • Time for one full rotation ("day"): 9.9 Earth hours

  • Has very energetic aurora

Saturn
Saturn image courtesy NASA/JPL/Space Science Institute
image courtesy NASA/JPL/Space Science Institute

 

Facts about Saturn:

Saturn is a massive planet surrounded by an outer layer of gases mostly made up of hydrogen and helium. A six-sided jet stream has been observed on Saturn's north pole.

Saturn is well-known for its visible rings mostly made of ice, dust, and rocks. The rings are about 400,000 km (240,000 mi) wide, the approximate distance from Earth to the moon. 

Saturn has 62 moons, 53 have been confirmed and nine are still being studied.

Saturn statistics:

  • Distance from the sun: 1.5 billion km (934 million mi)

  • Diameter: 9.45 x Earth

  • Mass: 95.2 x Earth

  • Time for one full orbit ("year"): 29.4 Earth years

  • Time for one full rotation ("day"): 10.7 Earth hours

  • Average density: Less dense than water

Uranus
Uranus image courtesy NASA/JPL
image courtesy NASA/JPL

 

Facts about Uranus:

Uranus is one of the ice giants. It has the third largest diameter of the planets in our solar system. Only Jupiter and Saturn are larger.

Uranus is mostly fluid. Trace amounts of methane in the atmosphere give the planet a blue color.

Uranus has 13 known rings and 27 small moons. It has auroras that are not aligned with the poles because of its lopsided magnetic field.

Uranus statistics:

  • Distance from the sun: 3.1 billion km (1.9 billion mi)

  • Diameter: 4.01 x Earth

  • Mass: 14.5 x Earth

  • Time for one full orbit ("year"): 84 Earth years

  • Time for one full rotation ("day"): 17.2 Earth hours

  • Rotates clockwise and on its side

Neptune
Neptune image courtesy NASA/JPL
image courtesy NASA/JPL

 

Facts about Neptune:

Neptune is an ice giant. It is the only planet in the solar system that cannot be seen with the naked eye. Its windy atmosphere is made up primarily of hydrogen, helium, and methane. 

Neptune has 13 confirmed moons and six faint rings. Neptune's largest moon, Triton, is the only large moon in the solar system that orbits its planet in the opposite direction from the planet’s rotation.

Neptune statistics:

  • Distance from the sun: 4.5 billion km (2.8 billion mi)

  • Diameter: 3.88 x Earth

  • Mass: 17.1 x Earth

  • Time for one full orbit ("year"): 165 Earth years

  • Time for one full rotation ("day"): 16 Earth hours

  • Solar system's windiest planet

Pluto
Pluto image courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
image courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

 

Facts about Pluto:

Pluto is no longer considered a planet. Pluto is considered  a dwarf planet, a category that includes Makemake, Haumea, and Eris.

Pluto has five moons. Its largest moon, Charon, is so big that Pluto and Charon orbit each other like a double planet.

Pluto is located in the Kuiper Belt, an area of space scientists are just beginning to study. The Kuiper Belt is a donut-shaped region of icy objects beyond the orbit of Neptune.

Pluto statistics:

  • Distance from the sun: 5.91 billion km (3.67 billion mi)

  • Diameter: 0.186 x Earth

  • Mass: 0.0025 x Earth

  • Time for one full orbit ("year"): 248 Earth years

  • Time for one full rotation ("day"): 153.3 Earth hours

  • Reclassified as a dwarf planet in 2006