1. Recent Studies of Mars: 2013- 2014 Richard W. Schmude, Jr. Gordon State College Barnesville, GA

2. Overview Purpose of work North Polar Cap (NPC) Hellas Brightness measurements

3. Purpose NPC interannual variability Hellas variability – Time of day – Year – season Brightness (visible & Near infrared)

4. Hubble Image Processed by P. James, T. Clancy, S. Lee and NASA

5. Introduction: Ls Ls rangeSeason (N. hemisphere) 0 – 90°Spring 90 – 180°Summer 180 – 270°Fall 270 – 0°Winter

6. Voting Questions Do not talk to anyone until after 1 st vote After 1 st vote – Talk to someone that you disagree with – Convince him/her that you are right – Listen to your partner

7. Voting Question If Ls = 135° it is ___________ in the northern hemisphere. a. late springb. mid spring c. early summerd. mid summer

8. Voting Question Ls = 50° is similar to _______ in the USA. a. Februaryb. June c. Octoberd. May

9. Method and Materials WinJupos – Name an image 2014-07-12-1320-name & other info. – Load an image – Software computes longitude & latitude

10. Polar Cap Measurement Goal: get all longitudes

11. NPC: Mean latitude

12. Hellas measurements Northern border measured – Every 5° of longitude – 270° W to 320° W – Red light images used – Mean values computed for each 5° of longitude

13. Why red light? green-left & red-right

14. Results: NPC in 2013 – 2014

15. Interannual variability Spring NPC – Mean latitudes (all longitudes) considered – Wilcoxon Signed Rank Test 90% confidence level As few as five values Non-parametric test

16. Data sets MGS: 2000, 2002, 2006*, 2007-08* Schmude: 2009-10, 2011-12, 2013-14 Individual latitudes are not reported

17. Results Year  mean latitude Comparison to 2000 2000---The standard 20020.9°Larger 2006~0.2°Probably the same 2007-08~0.6°Probably smaller 2009-100.8°Larger 2011-120.3°Same 2013-140.0°Same

18. Voting Question At Ls = 50°, the temperatures are __________ in the southern hemisphere of Mars. a. risingb. falling

19. Hellas: white layer Northern border – Clouds or frost? – Growth during fall? – Changes from morning to afternoon? – Interannual differences?

20. Hellas: white layer

21. Hellas: changes in Northern border Wilcoxon Signed Rank Test – Mid fall (1995) and late fall – early winter (2014) – Morning afternoon (2014) – 2012 and 2014 (similar seasons)

22. Statistical results: Hellas There is no statistical difference (90% conf.) – Mid fall and late fall/early winter – Morning and afternoon – 2012 and 2014 (similar seasons)

23. Brightness Measurements Purpose – Long-term changes – Water reservoirs – Dust storms – Brightness model of planet

24. Brightness in Magnitudes Zero magnitude = a flux of light As magnitude drops, brightness increases

25. Electromagnetic Radiation Electric wave Magnetic wave Velocity = 186,000 miles/hour (vacuum) Wavelength (length of one wave)

26. Electromagnetic radiation Wavelength and color FilterWavelengthColor V540 nmgreen R700 nmred J1250 nmnone H1650 nmnone

27. Previous work Schmude measured B, V, R and I brightness of Mars from 1991 to 2014 Mallama (2007) summarizes work up to 2005. Almost no work done for J and H filters

28. Near Infrared light

29. Voting question Please rank the objects from highest to lowest magnitude. a. Sun, full Moon, Venus b. Sun, Venus, full Moon c. Full Moon, Venus, Sun d. Venus, full Moon, Sun

30. Materials SSP-4 photometer Celestron CG-4 mount 0.09 m Maksutov telescope Extension cord (requires AC power)

31. Experimental set-up

32. Method of brightness measurement Sky brightness and then comparison star Sky brightness and then Mars Repeat 2 ½ more times Compute Mars’ magnitude Make corrections

33. Normalized Magnitude J(1,0) and H(1,0) Mars is 1 au from Earth and Sun Sunlight reflects directly back to observer (zero phase angle)

34. Results: Albedo

35. Light curve J filter

36. Light curve H filter

37. Conclusions NPC may undergo small changes from one year to the next Hellas white area: No change with respect to diurnal, seasonal or year to year cycles Mars’ albedo does not rise in near infrared Mars brightens as it rotates in the J & H filters