document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=548404>Question 548404</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I have an astronomy program that provides information on known comets.  They provide only two pieces of information:  Perhelion and eccentricity.\r<BR>\n" );
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document.write( " I have gone through a number of books and web pages both for astronomy problems and math problems trying to find out how to find out the length of the major axis.\r<BR>\n" );
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document.write( "I am not very good at working with advanced math (though I have studied some that I needed to use).  Please help me with this.  Thank you </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #356974 by </B><A HREF=/tutors/aboutme.mpl?userid=Alan3354><B>Alan3354(69443)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Alan3354><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=Alan3354><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=356974\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> I have an astronomy program that provides information on known comets.  They provide only two pieces of information:  Perhelion and eccentricity.\r<BR>\n" );
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document.write( " I have gone through a number of books and web pages both for astronomy problems and math problems trying to find out how to find out the length of the major axis.<BR>\n" );
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document.write( "The perihelion is the distance from one of the foci to the intersection of the ellipse its major axis.<BR>\n" );
document.write( "The distance from the center to the focus is a*e, where a = 1/2 the major axis and e is the eccentricity.<BR>\n" );
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document.write( "The perihelion, p = the distance from the focus to a, p = a - f<BR>\n" );
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document.write( "f = a*e<BR>\n" );
document.write( "p = a-f --> a = p+f<BR>\n" );
document.write( "a = p + a*e<BR>\n" );
document.write( "a - a*e = p<BR>\n" );
document.write( "a(1 - e) = p<BR>\n" );
document.write( "a = p/(1 - e)<BR>\n" );
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document.write( "major axis = 2p/(1 - e)<BR>\n" );
document.write( "That what you're looking for?<BR>\n" );
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document.write( "PS  Did you see the comet whose perihelion was only 120000 km from the Sun's surface?<BR>\n" );
document.write( "Comet Lovejoy.\r<BR>\n" );
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