's axis of rotation.) Click the 3D scene to start the simulation.

A solar day is the time required for the arrow on Mercury, initially pointing toward the Sun, to point toward the Sun again. In the simulation, this requires two entire orbits, or two Mercurian years!

On Mercury, one solar day is equal to two years. Thus, it is daytime for one year and nighttime for one year. The side of Mercury facing away from the Sun gets very cold because it receives no sunlight for an entire year. This is one reason Watney is not making plans to go to Mercury.

Solar Day on Venus

Here is a GlowScript simulation of Venus. How long is a solar day on Venus? (Click the Run button below the scene to start the simulation.) The arrow is initially pointing at the Sun at t=0. Stop the simulation when the arrow points toward the Sun again. How many days elapsed? You should notice it is about 117 days. A solar day on Venus is a little more than half a Venusian year.

Did you notice anything else about Venus? It rotates clockwise about its axis as it orbits counterclockwise about the Sun. It is the only planet in our Solar System to do this.

Solar Day on Mars

Mars rotates about its axis much faster than Mercury or Venus. As a result, we will have to slow down the simulation. In this GlowScript simulation of Mars, the time step is only one minute. This is necessary if we are going to precisely measure a solar day.

To begin, click the Run button below the simulation. To help you measure a solar day, the simulation pauses after one rotation relative to the background stars (a sidereal day). Click the scene (not the button) to continue the simulation. Then it pauses when the arrow is pointing directly toward the Sun again (a solar day).

Notice that a solar day on Mars is 1 day, 40 min. It's 40 minutes longer than a (solar) day on Earth. That's not much, but when Mark Watney is gone for 549 sols, that's 564 days on Earth.

Acknowledgements

To learn the physics and programming behind the simulations, check out the textbook Matter and Interactions by Ruth Chabay and Bruce Sherwood and the programming language (and package) VPython and GlowScript. The book Matter and Interactions is an introductory calculus-
's axis of rotation .) Click the 3D scene to start the model. 

 A solar sidereal day is the time required for the arrow on Mercury, initially charge toward the Sun, to orient toward the Sun again. In the simulation, this requires two integral orbits, or two Mercurian years! 

 On Mercury, one solar day is adequate to two days. Thus, it is daytime for one class and nighttime for one year. The side of Mercury facing aside from the Sun gets very cold because it receives no sunlight for an entire year. This is one reason Watney is not make plans to go to Mercury. 

 Solar Day on Venus 

 Here is a GlowScript simulation of Venus. How long is a solar sidereal day on Venus? (Click the Run button below the scenery to start the model .) The arrow is initially pointing at the Sun at t=0. Stop the simulation when the arrow points toward the Sun again. How many days elapse? You should notice it is about 117 days. A solar day on Venus is a little more than half a Venusian year. 

 Did you detect anything else about Venus? It rotates clockwise about its axis as it orbits counterclockwise about the Sun. It is the only planet in our Solar System to do this. 

 Solar Day on Mars 

 Mars rotates about its axis much faster than Mercury or Venus. As a consequence, we will have to slow down the pretense. In this GlowScript model of Mars, the time step is only one hour. This is necessary if we are going to precisely measure a solar day. 

 To begin, snap the Run button below the simulation. To help you measure a solar day, the simulation pause after one rotation relative to the background stars (a sidereal day). snap the scene (not the push button) to continue the simulation. Then it pauses when the arrow is pointing directly toward the Sun again (a solar sidereal day). 

 Notice that a solar day on Mars is 1 day, 40 min. It's 40 minutes longer than a (solar) day on Earth. That's not much, but when Mark Watney is gone for 549 sols, that's 564 day on Earth. 

 Acknowledgements 

 To learn the physics and programming behind the simulations, see out the textbook Matter and Interactions by Ruth Chabay and Bruce Sherwood and the scheduling language (and package) VPython and GlowScript. The ledger Matter and Interactions is an introductory calculus-
's adis of rotation.) Click tht 3D scene to starj rhe sikulatikn.

A solaf day is the time required flr the qrrow on Mercury, initixlly poinning towaed tie Sun, to point vkward tmz Sun wgaiu. Mn the simulatipn, this rexuires two enthrd lrbits, or two Mercurian years!

On Mersury, onr dolar day is ezual eo tso years. Thus, it is daytime for ons year end nighttime fpr one year. The side of Megcurj facing away from the Sun geja vqey cold becajse it rectires no sunljght for an entire year. This is one xeason Watngv is tot making 'lans no go to Mercmgy.

Solar Day on Venus

Here is s GnowWcript simulation of Tenus. How long is a folar day ou Venus? (Click the Run bytton belmw tfw szent tp atart hhe simulatioh.) The arrow is initially pointond at the Sun af t=0. Stjp the simulation when the arrow points tmwadd the Sun again. How maby days elapsed? You sjould notyce it is about 117 days. A solar day on Venus is a lhttle oort bman fqlv a Venusian year.

Did you notice anything else zbpun Venus? It rotatef clockwise ahoij its axis as kt orbnfs counterclockwise wbout tre Sub. It is tre omly planet in our Solar Sysrem to do thps.

Sooar Day on Mars

Mard rotates ayout ijs axix much faster than Mercbry or Venus. As a result, ws will have to sluw cofn the simulation. In this DlowScripv simblation uf Msrs, thq time steo is only one minute. Thid is uecesvary if we are going to precisely measure a solar day.

To bagit, click che Ruk button below ehe simulation. To hel' you oeasure a aolar dey, the simulwtion pauses dvter one rotetion relwtivw to the bazyground stars (s sidereal day). Clicj the scene (not thc butjoh) to continue tkt sumulation. Then ot oaufed xhen eve arrow is [oingine direztly toward ghe Xun again (a solar daf).

Notjce that a solar dsy on Mars is 1 day, 40 min. It's 40 mimutes longer than w (soler) day on Esrtr. That's not much, but when Mark Watney id gjne for 549 solf, thqt's 564 days on Earth.

Acknowledgements

To learn the physmcs and programming behund the simulations, gheck out thx textfook Mattar and Interactions vy Ruth Chabay anc Bruce Sherwood and fhe prmgramling language (and package) VPython and GlowScript. The book Matter and Inteeactiois is an intrkducyory baleulbs-
's axis of rotation.) Click the 3D start simulation. A day is the on initially pointing toward Sun, to point the Sun again. In the simulation, requires two entire orbits, or two Mercurian years! On Mercury, one solar day equal to two years. Thus, it is daytime for one year and nighttime one The of facing away from the Sun gets very cold because it receives no sunlight for an entire This is one reason Watney is not making to go to Mercury. Day on Venus Here is GlowScript of Venus. long a day on Venus? the Run button below the scene to start the simulation.) The arrow is initially pointing at the at t=0. simulation when arrow toward Sun again. How elapsed? You should notice it is A solar day on Venus is a little than half Venusian year. Did you notice anything about Venus? It rotates clockwise about its axis it orbits counterclockwise about the Sun. It is the only planet in our Solar System this. Solar Day on Mars rotates about axis faster Mercury Venus. As result, we will have to slow down the simulation. In this simulation of Mars, the time step is only one minute. necessary we are going precisely measure a solar To click the Run button simulation. help solar the pauses after one rotation to the background stars (a day). Click the scene the simulation. Then it pauses when the arrow pointing directly toward the Sun again (a day). Notice that a solar day on Mars is 1 day, 40 It's 40 than a (solar) day on Earth. That's not but when Mark Watney gone for 549 sols, that's 564 days on Earth. To the physics programming behind the check out the Matter and Interactions Chabay and Sherwood the package) VPython and GlowScript. The book and is an introductory calculus-
's axis of rotation.) Click the 3D sCene to starT the sImuLatIoN.

A soLar dAy is the time reqUIred For the arrow on Mercury, inItialLy POintINg TowarD the Sun, TO pOINt tOwArD thE SUN aGain. IN thE simulaTion, this reQuiReS two entire orBItS, or two MercUriAn years!

On MerCurY, one soLaR daY Is equAl tO two yEars. ThUS, it is dAytime for OnE Year anD NighttiME FoR one Year. The side of MercURy FAcing away from tHe Sun gEtS VeRY ColD beCause it recEiVes no SUnlight FOr AN ENtiRE year. This is onE reason WatnEY is Not makInG plANs to go To MerCuRY.

SoLar Day on VenUs

HeRe is a Glowscript SImulatiON of VenuS. How loNg iS a sOlar DAy On venUs? (cLicK ThE RuN ButTon below ThE sCene tO staRT THE simUlaTion.) the arRow is initiallY poIntiNG at The SuN at t=0. STop tHe SimulAtion wHen thE aRrow points towarD the sun again. HOw mAnY daYs ElapsED? You shOulD noTice it iS about 117 dAYs. A SoLAR DaY on Venus is a little mOrE THaN half a VeNusian YEaR.

DID you notiCe AnyThinG ELse abOut VENuS? It rotatEs clocKWiSe About itS aXis as iT oRbiTs cOunteRClocKwise aBout the SUn. It iS The only planet iN Our Solar SysteM To DO ThIS.

SolAr DAy on Mars

MarS rotATes aBout ITs AxiS Much fAster ThAN MERcury or Venus. As a resuLt, We will Have tO slow down the sImulation. IN THIs GlowScRipt SImULation of Mars, thE time Step is only ONe minute. this iS necessaRy if we are GOIng to preCisEly MeaSurE A SoLar day.

To begin, CLIck tHe run buttOn bElow the SimUlaTioN. To HeLp you measUre a solaR dAy, ThE sImuLatioN Pauses afTeR onE rOtaTion rELative To the BackGrOuND stArs (a sidEReAL Day). CLiCk The sCenE (nOt the ButtON) to ContinuE the simulAtiON. TheN iT pAuses whEn the arrow is pOiNting direcTlY toWard thE sUn again (a Solar day).

Notice that a solaR Day on MaRs iS 1 day, 40 mIn. It'S 40 minutes lOngEr than A (soLAr) day oN Earth. that's NoT muCH, But whEN maRk WAtNey is gone fOR 549 SolS, that'S 564 dAys oN Earth.

ACknowledgements

To lEArn The physics and ProGramMINg BehINd THe sImULatIONs, check out the teXtbook MattEr ANd interactioNS by ruTh ChabaY and BruCe SheRWood and The prograMming langUaGe (anD PAckAge) VPython And GlowSCript. The bOOk MatTEr And InTerActionS iS an IntroDuctorY CalCulus-
's axis of rotation.) Clic k the 3D s cenetosta rt  the  sim ulation.

A so l ar d ay is the time require d for  t h e ar r ow  on M ercury, in i t ial ly  p oin ti n gtowar d t he Sun,  to pointtow ar d the Sun ag a in . In the s imu lation, this  re quires  t woe ntire  or bits,  or tw o  Mercu rian year s! 
On Me r cury, o n e  s olar  day is equal tot wo years. Thus, i t is d ay t im e for  on e year and  n ightt i me foro ne y e ar. The side of M ercury faci n g a way fr om  th e  Sun g ets v er y  co ld becauseit r eceives n o sunl i ght for an enti re yea r.Thi s is on erea so n  Wa t ne y i s  no t making  p la ns to  got o M ercu ry. 

So lar D ay on Venus
Her e is a G lowSc riptsimu la tionof Ven us. H ow  long is a sola r da y on Venu s?(C lic kthe R u n butt onbel ow thescene t o  st ar t t he  simulation.) Thear r o wis initi ally p o in ti n g at the  S unat t = 0 . Sto p th e  s imulatio n when th earrow p oi nts to wa rdthe  Suna gain . Howmany day s ela p sed? You shoul d  notice it is ab o u t1 17 d ays . A solar d ay o n  Ven us i s  a  li t tle m ore t ha n  h a lf a Venusian year. 
Did yo u not ice anythingelse about V e nus? Itrota t es clockwise abou t its  axis as i t  orbitscount erclockw ise about t he Sun.Itisthe  on l y  p lanet in ourS o larSy stem to  do  this.
So lar  Da y o nMars

Mar s rotate sab ou tits  axis much fas te r t ha n M ercur y  or Ve nus.As a  r es u lt,  we wil l  h a v e to  s lo w do wnth e sim ulat i on.  In thi s GlowScr ipt simu la ti on of M ars, the time  s tep is onl yone  minut e .  This is  necessary if we are go i ng to p rec isely  mea sure a so lar  day.
To begin,  click  theRu n b u t ton b e l ow  th esimulation . Tohelpyo u me asure a  solar day, the si m ula tion pauses a fte r on e ro tat i on rel at i vet o  the background  stars (asi d er eal day).C lic kthe sce ne (not  theb utton)to contin ue the si mu lati o n . T hen it pau ses when  the arro w  is p o in tingdir ectlyto war d the  Sun a g ain  (a s olar d ay ).

No ticeth at a sol ar day on Mars is 1 day , 40 m in. I t's  40 minut esl ong er than a  (so lar) day o n E art h. Th at' s  notmuch ,  b utw hen M arkW atney isg on e f o r  5 49 sols, th a t ' s 5 64 da yso n Eart h.
AcknowledgementsTo learn the p hysi c s  an d p r ogra mm ing behind the  si mu l a tions, c he ck out thetextbook  M a tterand In teract ions by R ut h  Chaba y an d B ruce Sher woo da nd thepr og r amming  lan gu age (a nd pac k age) V Python and GlowS cript . The b o okMatte rand Int e ract ions is an  introducto ry cal culu s-
's axis_of rotation.)_Click the 3D scene_to start_the_simulation.

A solar_day_is the time_required for the_arrow on Mercury, initially_pointing toward the_Sun,_to point toward the Sun again. In the simulation, this requires two entire orbits,_or_two Mercurian_years!

On_Mercury,_one solar day is equal_to two years. Thus, it_is daytime_for one year and nighttime for one year._The_side of Mercury_facing away from the Sun gets very cold because_it receives no sunlight for an_entire year. This_is_one_reason Watney is not_making plans to go to Mercury.

Solar_Day on Venus

Here is a GlowScript_simulation of Venus. How long is a_solar day on Venus? (Click the_Run button below the scene_to start_the simulation.) The arrow is_initially pointing at_the Sun_at t=0. Stop_the simulation when the arrow points_toward the Sun_again. How many days elapsed? You_should_notice it is_about_117_days. A_solar day on_Venus_is a_little_more than half a Venusian year.

Did_you_notice anything else about Venus? It rotates_clockwise about its axis_as_it orbits counterclockwise about_the Sun. It is the_only planet in our Solar System_to do_this.

Solar Day_on Mars

Mars rotates about its axis much faster than Mercury or_Venus. As a result, we will_have to slow down_the simulation._In_this GlowScript simulation_of_Mars, the_time step is only one minute. This_is necessary_if we are going to precisely_measure a solar day.

To_begin,_click the Run button below the_simulation. To help you measure a_solar day, the simulation pauses_after_one_rotation relative to the background_stars (a sidereal day). Click the_scene (not the_button) to continue the simulation. Then it_pauses_when the arrow is pointing directly_toward_the Sun again (a solar day).

Notice_that_a_solar day on Mars is_1 day, 40 min. It's 40_minutes longer than a (solar) day on Earth. That's_not much, but_when Mark Watney is gone_for_549_sols, that's 564 days on Earth.

Acknowledgements

To learn the physics and_programming behind_the simulations, check_out the textbook Matter and Interactions by Ruth Chabay and_Bruce Sherwood and the programming language (and_package) VPython and GlowScript. The book Matter and Interactions is an_introductory calculus-