Kitt Peak Nightly Observing ProgramSplendors of the Universe on YOUR Night!

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Betelgeuse (also called Alpha Orionis, α Orionis, orα Ori) is one of the brightest and largest known stars,though it is not one of the most massive. Locatedapproximately 600 light­years from Earth, it is partof the constellation Orion and a vertex of the WinterTriangle asterism. Its large volume suggests that if itwere at the center of the Solar System, it wouldwholly engulf Mercury, Venus, Earth, and Mars,with its surface extending out to between the orbitsof Mars and Jupiter. It is classified as a redsupergiant and as a semiregular variable star—thatis, it shows considerable periodicity as its lightchanges, but this periodicity is sometimes irregular.

In the handle of the Big Dipper,Mizar & Alcor (ζ & 80 UrsaeMajoris) or the “Horse &Rider” form a naked­eye doublestar. They are traveling throughspace together about 80 light­years away from us, separatedby about a light­year. However,it is unknown if they areactually orbiting each other. Atelescope splits Mizar itself intotwo stars, but these both areagain doubles, bringing the totalin this system to six.

M44: The "Beehive Cluster." A large, bright, diffuseopen star cluster containing about 400 stars. It lies fairlyclose at a distance of under 600 lightyears away. Anothernickname: "Praesepe."

M45: The "Pleiades," the "Seven Sisters," or "Subaru". Abright, nearby star cluster in the last stages of star

formation. It has six to seven bright stars along withhundreds of fainter stars. It lies about 440 lightyearsaway and is around 100 million years old.

The Hyades is the nearest open cluster to the SolarSystem at about 150 light­years away and thus oneof the best­studied of all star clusters. It consists of aroughly spherical group of hundreds of stars sharingthe same age, place of origin, chemical content, andmotion through space. The Hyades Cluster appearsin the constellation Taurus, where its brightest starsform a V shape along with the brighter red giantAldebaran, which is not part of the cluster, merelylying along our line of sight. The age of the Hyadesis estimated to be about 625 million years. Thecluster core, where stars are most densely packed,has a diameter of about 18 light years. However,about one­third of confirmed member stars havebeen observed well outside this boundary, in thecluster's extended halo; these stars are probably inthe process of escaping from its gravitationalinfluence.

"Double Cluster" (NGC 884 and NGC 869): These twostar clusters are a treat for binoculars and telescope alike.Each is a congregation of many hundred stars around 50­60 light years in diameter. These clusters are both about7500 light years away.

M42: The Great Orion Nebula. This is a region of starformation about 1,300 ly away. It is roughly 30 ly acrossand contains enough material to make 2,000 stars the sizeof our sun.

Mars, the red planet, has a thin carbon dioxideatmosphere, clouds, dust storms, and polar caps made ofdry ice. Images of dry riverbeds from orbiting spacecraftshow us that liquid water once flowed on the Martiansurface.

Jupiter is the largest planet in the Solar System, a “gasgiant” 11 Earth­diameters across. Its atmosphere containsthe Great Red Spot, a long­lived storm 2­3 times the sizeof the Earth. The 4 large Galilean satellites and at least63 smaller moons orbit Jupiter.

The same side of the Moon always faces Earth becausethe lunar periods of rotation and revolution are the same.The surface of the moon is covered with impact cratersand lava­filled basins. The Moon is about a fourth ofEarth's diameter and is about 30 Earth­diameters away.

Quick streaks of light in the sky called meteors, shootingstars, or falling stars are not stars at all: they are smallbits of rock or iron that heat up, glow, and vaporize uponentering the Earth's atmosphere. When the Earthencounters a clump of many of these particles, we see ameteor shower lasting hours or days.

Satellites: Human technology! There are almost 500 ofthese in Low Earth Orbit (we can't see the higher ones).We see these little "moving stars" because they reflectsunlight.

Scintillation: The twinkling of star light is a beautifuleffect of the Earth's atmosphere. As light passes throughour atmosphere, its path is deviated (refracted) multipletimes before reaching the ground. Stars that are near tothe horizon will scintillate much more than stars highoverhead since you are looking through more air (oftenthe refracted light will display individual colors). In

space stars would not twinkle at all­ and this is the wayastronomers would like it if they could control the effectsof this troubling twinkle.

The Engagement Ring: Through binoculars, theNorth Star (Polaris) seems to be the brightest on asmall ring of stars. Not a constellation or cluster, thisasterism looks like a diamond engagement ring onwhich Polaris shines brightly as the diamond.

Your Telescope Operator and Guide. Thank you forjoining me this evening! See you soon!!

The web page for the program in which you just participated is at Nightly ObservingProgram. Most of the above images were taken as part of the Overnight TelescopeObserving Program. For more information on this unique experience please visitOvernight Telescope Observing Program.Copyright © 2015 Kitt Peak Visitor Center