(737640398) Astro 101 Weekly Project 1

7/24/2019 (737640398) Astro 101 Weekly Project 1

1/6

Jeevan Netraaj Singh Sidhu

Discussion Section 005

GSI: Mr. Dan Abramov

Astronomy 101 Fall 2015

Weekly Project 1

1. At selected times (i.e. during a total eclipse) the angular size of the moon and the Sun are exactlyequal. a. What parameters do these angular sizes depend upon?b. ompute the radius of the Sun in units of the moon!s radius. Sho" your calculations# and cite the

sources of the information you needed to loo$ up to sol%e this problem.An swer

a. &hysical (actual) size and distance

b.

Radius of the moon =

2

(2

=360

2

0.5 2 3!000

=2

= 16"5.51602 km

~1676km

0.5 150 , 000 , 002 0

Radiusofthesun=360

2

= 654,498.4695 km

~ 654,498 km

Hence,

65!# !$ km

= 3$0.511$16"6~91

!he "adius of the #un is a$$"o%imate&' 91 times the "adius of the moon

(itatio n

)ennett, *eff"e', +ean -onahue, icho&as #chneide" and +a"k /oit. The Cosmic Perspective: The solar System.

)oston ea"son, 2014. "int.

%

360


2/6

'. Suppose you had a car that could go any"here at a constant speed of 1$mhr (*' mihr)# e%en in space.+a$e sure to cite the sources for information you needed to loo$ up to sol%e the problem.

a. ,o" long "ould it ta$e to dri%e around the -arth!s circumference at the equator? Assume that you candri%e across both land and oceans.

. Suppose "e left the -arth. ,o" long "ould it ta$e to dri%e to the Sun?c. ,o" long "ould it ta$e (in years) to dri%e the . light years to the nearby star Alpha entauri?

An swer

a. 3a"ths ci"cumfe"ence = 2 22222222222

= 2 67822222222222= !00"! km

!00"!

100

&

= !00."! 'ors

)ence# to tra*el !00"!km +,t' a car t'at can tra*el at 100km&'# ,t +,ll take !00."! 'ors.

b. -art'/n ,stance= 150#000#000 km

150#000#000

100&

=1#500#000 'ors

)ence# to tra*el 150#000#000km +,t' a car t'at can tra*el at 100km&'# ,t +,ll take 1#500#000

'ors

c.

1 l,'t year $.!6 1012

4.4 4.1624 101 !.162! 1013

100 &= !.162! 10

11

)ence# to tra*el !.! l,'t years +,t' a car t'at can tra*el at 100km&'#

it i&& take 4.1624 1011

,t a t , on

)ennett, *eff"e', +ean -onahue, icho&as #chneide" and +a"k /oit. The Cosmic Perspective: The solar

System. )oston ea"son, 2014. "int.


3/6

/. 0f you "ere on +ars "ould &olaris still be the orth Star? -xplain your ans"er in around 1 "ords# andorusing a carefully dra"n diagram.

An swer

4n s'ort# no. -art's a,s t,lte 7y 23.5 8rom a l,ne

9er9en,clar to t'e

ecl,9t,c 9lane. 4t so 'a99ens t'at t'e t,lt makes t'e -art' to 7eor,entate so

t'at ,t 9o,nts almost ,rectly to t'e :ort' /tar (Polar,s%. 48 +e+ere to 7e on

mars# ,ts a,s t,lt +ol 7e 25. As a reslt o8 t'e *ar,at,on ,n

,ts a,s t,lt# ;ars

+ol not 7e 9o,nt,n to+ars Polar,s 7t ,nstea at a ,e. 18 #e$t. 2015.


4/6

. 0magine a ci%ilization that decided to colonize nearby habitable "orlds. 2he ci%ilization sends out one colonyship# "hich establishes a colony. 1# years later# the original "orld and the ne" colony each send out acolony ship# "hich themsel%es establish colonies. 1# years later# the original "orld and each colony eachsend out a colony ship# "hich establish colonies. 2he process continues.

a. 3ra" a graph of the number of "orlds (the original "orld and colonized "orlds)# continuing to the first1# years. +a$e sure to label your axes.

b. ,arder 4 Write an expression for the number of "orlds as a function of time t

c. ,arder4 Assuming this rate of gro"th can be sustained# ho" long "ould it ta$e for this ci%ilization to fill up1 billion a%ailable "orlds? An approximate calculation is 56# if you state your approximations or processfor reaching your ans"er.

d. ,umanity has not yet succeeded in its search for intelligent extra7terrestrial life. 0n the context of your ans"ertopart c# describe in around 1 "ords some possible explanations for our failure to detect intelligent alienlife (if you didn!t ans"er part c# ne%er fear 7 explain one or more possible solutions to the 8ermi &aradox).

.An swe r

1200

Number of worlds in the rst 100,000

years1000 102!

00

600512

nm7er o8+orls

!00

200

0

6!1 2 ! 1632

12

256

0 10000 20000 30000 !0000 50000 60000 "0000 0000 $0000 100000 110000

Number ofYears

a.

. ft= 21000

NumberofWorlds


5/6

0

c. 8(t%= 210000

#

+'en t=100000# nm7er o8 +orls ,s 102!.

48 t= 300000# nm7er o8 +orls +ol 7e 1#0"3#"!1#2!

300#000

hence, f00,000= 2 10000= 1#0"3#"!1#2!

?r

)ence#

210 = 1024

(210

%

= (102!%

2

30

=1#0"3#"!1#2!


6/6

F,ll,n 9 1 7,ll,on +orls +ol take a99ro,mately 300#000years.

. 4t m,'t 7e 9oss,7le t'at ,n t'e contet o8 t'e arment#

+e are s99ose to 7e t'e 8,rst ones to colon,@e a +orl.

/,nce +e 'a*e not reac'e t'e tec'nolo,cal ca9a7,l,t,es to

colon,@e anot'er 9lanet# ,t m,'t 7e t'e

reason +'y t'ere ,s no ot'er ,ntell,ent l,8e ,n s9ace.

Anot'er reason m,'t 7e t'at +e are look,n 8or ,ntell,ent

l,8e s,n t'e +ron met'os. We are sen,n ra,o +a*es

,nto s9ace to look 8or a s,nal. 4t m,'t 7e 9oss,7le

t'at as +e 'a*e come a7ot to se ra,o +a*es# ot'er

more a*ance c,*,l,@at,ons 'a*e 7een s,n ot'er k,no8 tec'noloy to reac' s. >',s ,

Documents

(737640398) Astro 101 Weekly Project 1