What’s all the hoopla What’s all the hoopla

with with Mars?Mars?

Mars in the NewsMars in the News

Mars to Get Closer than Ever in Mars to Get Closer than Ever in recorded History in 2003 (recorded History in 2003 (www.space.com))

Mars making closest approach to Mars making closest approach to Earth in 60,000 years (Earth in 60,000 years (http://www.cnn.com/))

Is this my one chance to see Is this my one chance to see Mars??Mars??

No! Nein! Nyet!No! Nein! Nyet!

You can see Mars nearly throughout You can see Mars nearly throughout any given year, you just may have to any given year, you just may have to look at an odd hour! And Mars will be look at an odd hour! And Mars will be

prominent in the evening roughly prominent in the evening roughly every two years.every two years.

So why the hoopla?So why the hoopla?

Three things happen the week of 25 Aug Three things happen the week of 25 Aug 20032003

Mars is at perihelionMars is at perihelion Mars is at oppositionMars is at opposition Mars-Earth distance very smallMars-Earth distance very small

So why is all that important?So why is all that important? Mars appears bigger, brighter and is Mars appears bigger, brighter and is

visible all night.visible all night. ““full-moon effect”full-moon effect”

DefinitionsDefinitions EllipticalElliptical PerihelionPerihelion AphelionAphelion OppositionOpposition

What is perigee and apogee?Hint: Geology, Geography

Bonus: What is periastron?Hint: Astronomy

Is a circle an ellipse?Yes, it is the ‘perfect’ ellipse with eccentricity = 0

So why the hoopla?So why the hoopla?

Three things happen Three things happen the week of 25 the week of 25 AugAug

Mars is at Mars is at perihelionperihelion

Mars-Earth Mars-Earth distance very distance very smallsmall

Mars is at Mars is at oppositionopposition

FactsFacts

Orbital parametersOrbital parameters MarsMars EarthEarth

Sidereal orbit period Sidereal orbit period (days)(days)

686.980686.980(~22 (~22 months)months)

365.256365.256

Perihelion (10Perihelion (1066 km) km) 206.62206.62 147.09147.09

Aphelion (10Aphelion (1066 km) km) 249.23249.23 152.10152.10

Synodic period (days)Synodic period (days)779.94779.94(~26 (~26 months)months)

Mean orbital velocity Mean orbital velocity (km/s)(km/s)

24.1324.13 29.7829.78

Orbit eccentricityOrbit eccentricity 0.09350.0935 0.01670.0167

Length of day (hrs)Length of day (hrs) 24.659724.6597 24.000024.0000

More realisticMore realisticStart 03/21/2001

Opposition 06/13/2001

Opposition 08/28/2003

Opposition 11/07/2005

Animation made using Starry Night Pro 4

The Planet Mars: A History of Observation and DiscoveryWilliam Sheehan

DateDate AngulaAngular sizer size

Distance Distance from Earth from Earth

(AU)(AU)

2001 Jun 2001 Jun 1313

20.5”20.5” 0.4560.456

2003 Aug 2003 Aug 2828

25.1”25.1” 0.3730.373

2005 Nov 72005 Nov 7 19.8”19.8” 0.4700.470

The animation starts on 03/21/2001, shortly before the opposition in 2001, and shows the Earth catching up to and then passing Mars. The animation continues through the opposition in 2003 and ends on the opposition in 2005. Although Mars only takes about 22 months to go around the sun once, by the time we catch up to it, it is 4 months further along in its orbit from the previous opposition, hence the shift in the position of opposition and why not every opposition is a close one… just the ones occurring near Mars’ perihelion point.

Future OppositionsFuture Oppositions

Other Close ApproachesOther Close ApproachesRank / DateRank / Date Miles Apart Miles Apart Kilometers Kilometers

57,617 B.C. Sep. 57,617 B.C. Sep. 1212

34,622,00034,622,000 55,718,0055,718,0000

#10 #10 1403 July 311403 July 31 34,729,75934,729,759 55,892,13155,892,131

# 9 # 9 1640 Aug. 201640 Aug. 20 34,716,35034,716,350 55,870,55155,870,551

# 8# 8 1198 Aug. 3 1198 Aug. 3 34,714,91234,714,912 55,868,23655,868,236

# 7# 7 1119 July 31 1119 July 31 34,709,47634,709,476 55,859,48855,859,488

# 6# 6 1766 Aug. 13 1766 Aug. 13 34,696,71334,696,713 55,838,94855,838,948

# 5# 5 1561 Aug. 7 1561 Aug. 7 34,695,98734,695,987 55,837,78055,837,780

# 4# 4 1482 Aug. 3 1482 Aug. 3 34,677,85234,677,852 55,808,59455,808,594

# 3# 3 1845 Aug. 18 1845 Aug. 18 34,674,47734,674,477 55,803,16355,803,163

# 2# 2 1924 Aug. 22 1924 Aug. 22 34,658,18234,658,182 55,776,93955,776,939

# 1 2003 Aug. 27# 1 2003 Aug. 27 34,646,41834,646,418 55,758,0055,758,0066

2287 Aug. 292287 Aug. 29 34,603,17034,603,170 55,688,40555,688,405

So we don’t have to wait another 60,000 years!

Why??Why??

Orbits are not static… they are being Orbits are not static… they are being affected by the other planets… Mars’ affected by the other planets… Mars’ is becoming more eccentric…is becoming more eccentric…

So Mars is technically So Mars is technically closer…closer… Something far away looks smaller Something far away looks smaller

than same object that is closer.than same object that is closer. Well, if Mars is closer, then it looks Well, if Mars is closer, then it looks

bigger (and brighter).bigger (and brighter). If it is bigger, you don’t need as If it is bigger, you don’t need as

much ‘magnification’ or you can use much ‘magnification’ or you can use more and see more detail.more and see more detail.

Why this week?Why this week?

Actually, many amateurs have already Actually, many amateurs have already been observing Mars for several been observing Mars for several months!months!

It is now becoming visible earlier and It is now becoming visible earlier and earlier in the evenings (rather than earlier in the evenings (rather than having to get up at 2am!)having to get up at 2am!)

Closest approachClosest approach 09:52 UT 27 Aug 200309:52 UT 27 Aug 2003 OppositionOpposition 18:00 UT 28 Aug 200318:00 UT 28 Aug 2003 Mars at perihelionMars at perihelion ~10:45 UT 30 Aug 2003~10:45 UT 30 Aug 2003 It’s all down hill from here!It’s all down hill from here!

Visibility zonesVisibility zonesevening

morning

midnightNot visible, too close to the sun!

Inner planet (Mercury or Venus)

Earth’s orbit

Outer planet (Mars, Jupiter, Saturn, Uranus, Neptune, or Pluto)

27 Aug 2002!27 Aug 2002!

This and following slides show position of Earth and Mars over several months… can show how Mars was behind the sun (not visible), then in the morning sky and how it transitions to the evening sky.

30 Dec 200230 Dec 2002

30 March 200330 March 2003

30 June 200330 June 2003

27 Aug 200327 Aug 2003

30 Sep 200330 Sep 2003

30 Oct 200330 Oct 2003

30 Nov 200330 Nov 2003

30 Dec 200330 Dec 2003

Mars ImagesMars Images

21 Aug 2003Jeff Forsythhttp://www.teamforsyth.com/mars.html

17 July

15 August

E. WarnerNotice- Phase- Angular size- Polar cap size

Mars Previewer II

Compare to above image…The “eye” is Solis Lacus

“gibbous”

“full Mars”