Recent Studies of Mars: 2013-2014

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

6. Voting Questions • Do not talk to anyone until after 1st vote • After 1st 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 spring b. mid spring c. early summer d. mid summer

8. Voting Question Ls = 50° is similar to _______ in the USA. a. February b. June c. October d. 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 MeasurementGoal: 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

18. Voting Question At Ls = 50°, the temperatures are __________ in the southern hemisphere of Mars. a. rising b. 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 radiationWavelength and color

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 • CelestronCG-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