Light Years Away …..Light Years Away …..

Distances to Common Celestial Distances to Common Celestial BodiesBodies

How Far is a Light Year????How Far is a Light Year????

A A light-yearlight-year is equal to: is equal to:9,460,730,472,580.8 kilometers 9,460,730,472,580.8 kilometers about 5,879,000,000,000 miles about 5,879,000,000,000 miles about 63,240 astronomical unitsabout 63,240 astronomical units

The The astronomical unitastronomical unit ( (AU) AU) is a unit of is a unit of length equal to the distance from the Earth to length equal to the distance from the Earth to the Sun (about 93 million miles). the Sun (about 93 million miles).

How fast is Light??How fast is Light??

Reflected sunlight from the Reflected sunlight from the Moon's surface takes 1.2-1.3 Moon's surface takes 1.2-1.3 seconds to travel the seconds to travel the distance to the Earth.distance to the Earth.

The average distance from The average distance from

the Earth to the Moon is the Earth to the Moon is 384,403 kilometers or 384,403 kilometers or (238,857 miles) (238,857 miles)

How Long From the Sun to the How Long From the Sun to the Earth???Earth???

It takes It takes approximately 8.31 approximately 8.31 minutes for light to minutes for light to travel from the Sun travel from the Sun to the Earth. to the Earth.

This distance is This distance is referred to as One referred to as One Astronomical Unit Astronomical Unit (AU). (AU).

What about Pluto???What about Pluto??? It takes It takes

approximately 5.5 approximately 5.5 light-hours from light light-hours from light to travel to the to travel to the surface of Plutosurface of Pluto

Pluto’s orbit takes it Pluto’s orbit takes it from 29 to 49 AU from 29 to 49 AU (2.7–4.5 billion mi) (2.7–4.5 billion mi) from the Sun from the Sun

Pluto is mostly brown. No spacecraft has yet visited this distant object in our Solar

System

What is a Light Day Away??What is a Light Day Away??

The most distant The most distant space probe, space probe, Voyager 1, was Voyager 1, was about 28 light-hours about 28 light-hours (round-trip light time) (round-trip light time) away from Earth in away from Earth in the week ending the week ending March 9, 2007. March 9, 2007.

It took that space It took that space probe 30 years to probe 30 years to cover that distancecover that distance

How fast Can Astronauts Travel???How fast Can Astronauts Travel???

If we use the calculations If we use the calculations from the previous slide, from the previous slide, Voyager traveled ½ light Voyager traveled ½ light day in approximately 15 day in approximately 15 years. years.

If we travel at the speed of If we travel at the speed of the Voyager then it would the Voyager then it would take approximately 30 take approximately 30 years to travel one light years to travel one light day day

One light year would take One light year would take over 11,000 years!!!!!over 11,000 years!!!!!

The Oort Cloud??The Oort Cloud?? The Oort cloud is The Oort cloud is

nearly a light year nearly a light year from the sun and from the sun and approximately 2 approximately 2 light-years in light-years in diameter. diameter.

The Oort cloud, is a The Oort cloud, is a spherical cloud of spherical cloud of comets situated comets situated about 50,000 AU about 50,000 AU from the Sun. from the Sun.

This is This is approximately 1000 approximately 1000 times the distance times the distance from the Sun to from the Sun to Pluto Pluto Sedna is the outmost celestial body in our

Solar System

Alpha Centauri is the closest star system to our own Alpha Centauri is the closest star system to our own solar system at 4.37 light-years away solar system at 4.37 light-years away

(about 25.8 trillion miles or 277,600 AU).(about 25.8 trillion miles or 277,600 AU).

What About the Nearest Star??What About the Nearest Star??

What About Our Milky What About Our Milky Way Galaxy??Way Galaxy??

The center of our galaxy, The center of our galaxy, the Milky Way, is about the Milky Way, is about 2600 light years away. 2600 light years away.

The Milky Way Galaxy as seen from Death Valley, California

Infrared image of the Milky Way. Many of the stars in this image

cannot be seen in visible light

What About the Nearest Galaxy??What About the Nearest Galaxy??

The The Andromeda GalaxyAndromeda Galaxy is a spiral galaxy approximately is a spiral galaxy approximately 2.5 million light-years away.2.5 million light-years away.

It is the nearest galaxy to our It is the nearest galaxy to our own, the Milky Way.own, the Milky Way.

Andromeda is the largest Andromeda is the largest galaxy of a group of galaxies, galaxy of a group of galaxies, which consists of the which consists of the Andromeda Galaxy, the Andromeda Galaxy, the Milky Way Galaxy, the Milky Way Galaxy, the Triangulum Galaxy, and Triangulum Galaxy, and about 30 other smaller about 30 other smaller galaxies.galaxies.

How Far Can I See??How Far Can I See?? The Triangulum The Triangulum

Galaxy is a spiral Galaxy is a spiral galaxy galaxy approximately 3 approximately 3 million light-years million light-years away away

The Triangulum The Triangulum Galaxy is the most Galaxy is the most distant object that distant object that can be seen without can be seen without the use of a the use of a telescope telescope

Work CitedWork Cited

Slide 3:Slide 3: Surface of the Moon, Surface of the Moon, http://en.wikipedia.org/wiki/Image:Moon-Mdf-2005.jpghttp://en.wikipedia.org/wiki/Image:Moon-Mdf-2005.jpg

August 25, 2007 August 25, 2007 Slide 4: Slide 4: Surface of the Earth,Surface of the Earth,

http://en.wikipedia.org/wiki/Image:The_Earth_seen_from_Apollo_17.jpghttp://en.wikipedia.org/wiki/Image:The_Earth_seen_from_Apollo_17.jpg August 25, 2007 August 25, 2007 Slide 5: Slide 5: Surface of Pluto, Surface of Pluto, http://en.wikipedia.org/wiki/Image:Pluto.jpghttp://en.wikipedia.org/wiki/Image:Pluto.jpg August 25, 2007 August 25, 2007 Slide 6: Slide 6: Voyager 1, Voyager 1, http://en.wikipedia.org/wiki/Image:Voyager.jpghttp://en.wikipedia.org/wiki/Image:Voyager.jpg August 25, 2007 August 25, 2007 Slide 7: Slide 7: Space Shuttle in Orbit, http://www.archives.gov/press/press-kits/picturing-the-Space Shuttle in Orbit, http://www.archives.gov/press/press-kits/picturing-the-

century-photos/images/space-shuttle-challenger.jpg August 25, 2007century-photos/images/space-shuttle-challenger.jpg August 25, 2007 Slide 8:Slide 8: Diagram of the Distance of the Oort Cloud, Diagram of the Distance of the Oort Cloud,

http://en.wikipedia.org/wiki/Image:Oort_cloud_Sedna_orbit.jpghttp://en.wikipedia.org/wiki/Image:Oort_cloud_Sedna_orbit.jpg August 25, 2007 August 25, 2007 Slide 9:Slide 9: Position of Alpha Centauri, Position of Alpha Centauri,

http://en.wikipedia.org/wiki/Image:Position_Alpha_Cen.pnghttp://en.wikipedia.org/wiki/Image:Position_Alpha_Cen.png August 25, 2007 August 25, 2007 Slide 10:Slide 10: Infrared Image of Milky Way, Infrared Image of Milky Way,

http://en.wikipedia.org/wiki/Image:Milky_Way_IR_Spitzer.jpghttp://en.wikipedia.org/wiki/Image:Milky_Way_IR_Spitzer.jpg August 25, 2007 August 25, 2007

Milky Way Galaxy from Death Valley, Milky Way Galaxy from Death Valley, http://en.wikipedia.org/wiki/Image:Deathvalleysky_nps_big.jpghttp://en.wikipedia.org/wiki/Image:Deathvalleysky_nps_big.jpg August 25, 2007 August 25, 2007

Slide 11: Slide 11: Andromeda Galaxy, http://en.wikipedia.org/wiki/Image:M31_Lanoue.png Andromeda Galaxy, http://en.wikipedia.org/wiki/Image:M31_Lanoue.png August 25, 2007 August 25, 2007

Slide 12Slide 12: : Triangulum Galaxy, http://en.wikipedia.org/wiki/Image:PIA03033.jpg Triangulum Galaxy, http://en.wikipedia.org/wiki/Image:PIA03033.jpg August 25, 2007 August 25, 2007