What’s all the hoopla with

Mars?

Elizabeth WarnerUM Observatorywww.astro.umd.edu/openhouse

Mars in the News

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

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

Is this my one chance to see Mars??

No! Nein! Nyet!

You can see Mars nearly throughout any given year, you just may have to look at an

odd hour! And Mars will be prominent in the evening roughly every two years.

So why the hoopla?

Three things happen the week of 25 Aug 2003• Mars is at perihelion• Mars is at opposition• Mars-Earth distance very small

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

night.• “full-moon effect”

Definitions• Elliptical

• Perihelion

• Aphelion

• Opposition

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?

Three things happen the week of 25 Aug

• Mars is at perihelion• Mars-Earth distance

very small• Mars is at opposition

Facts

Orbital parameters Mars Earth

Sidereal orbit period (days)

686.980(~22 months)

365.256

Perihelion (106 km) 206.62 147.09

Aphelion (106 km) 249.23 152.10

Synodic period (days)779.94(~26 months)

Mean orbital velocity (km/s)

24.13 29.78

Orbit eccentricity 0.0935 0.0167

Length of day (hrs) 24.6597 24.0000

More 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

Date Angular size

Distance from Earth

(AU)

2001 Jun 13

20.5” 0.456

2003 Aug 28

25.1” 0.373

2005 Nov 7 19.8” 0.470

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 Oppositions

Other Close ApproachesRank / Date Miles Kilometers

57,617 B.C. Sep. 12

34,622,000 55,718,000

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

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

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

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

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

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

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

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

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

# 1 2003 Aug. 27 34,646,418 55,758,006

2287 Aug. 29 34,603,170 55,688,405

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

Why??

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

So Mars is technically closer…• Something far away looks smaller than same

object that is closer.

• Well, if Mars is closer, then it looks bigger (and brighter).

• If it is bigger, you don’t need as much ‘magnification’ or you can use more and see more detail.

Why this week?

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

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

• Closest approach 09:52 UT 27 Aug 2003

• Opposition 18:00 UT 28 Aug 2003

• Mars at perihelion ~10:45 UT 30 Aug 2003

• It’s all down hill from here!

Visibility 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!

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 2002

30 March 2003

30 June 2003

27 Aug 2003

30 Sep 2003

30 Oct 2003

30 Nov 2003

30 Dec 2003

Mars 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”

Good Websites

• http://www.theman.themoon.co.uk/Beginners/mars_at_opposition.htm

• http://www.uapress.arizona.edu/online.bks/mars/appends.htm

• http://www.seds.org/~spider/mars/mars.html

• http://www.space.com/spacewatch/mars_10_closest_030822.html

• http://www.kidscosmos.org/kid-stuff/mars-oppositions.html

• http://www.celestron.com/mars/

• http://www.badastronomy.com/bad/news/marsattacks.html

• http://skyandtelescope.com/observing/objects/planets/article_970_1.asp

• http://skyandtelescope.com/observing/objects/planets/article_997_1.asp

• http://www.floridastars.org/marsopp.2003.html