Mars Rise, Transit and Set Times for 2007

The following table lists the rising, transiting and setting times of Mars for a variety of latitudes from August to December 2007 (rising, transiting and setting times for the period from January to May 2008 can be seen here).

To find the appropriate times for any given location, the procedure is as follows:

1. Select the latitude which lies closest to your own location - the latitudes listed are 60º North, 50º North, 40º North, 30º North, 20º North, 0º (Equator), 15º South, 25º South and 35º South (if your latitude lies between any two of these, the times can be estimated by interpolating between the times given under the latitudes to either side). If you are unsure of your latitude and longitude, visit the Heavens Above website, select your country and enter the name of your nearest town or city using the 'Town Search' facility. For these purposes, latitude and longitude need only be taken to the nearest whole degree.

2. Select the required date and note down the rise, transit and set times shown in the relevant latitude column (dates are listed at 7 or 8 day intervals; if the required date is not listed, the times can be estimated by interpolating between that of the previous date and that of the following date),

3. If Daylight Savings Time (DST) is operating in your country, ADD ONE HOUR to the times you have noted down,

4. If your observing location is situated on - or very close to - the central longitude of your Time Zone, the times you have noted down will be accurate to within about 4 minutes. If, on the other hand, your observing location does not lie along  - or close to - the central longitude of your Time Zone (say, more than 2º away from it), you will need to apply a correction to the times you have noted down to allow for your own longitudinal position within your Time Zone (for any given location, this time correction needs only to be calculated ONCE, after which the same time correction will be applied to all times derived from the table),

5. Find the directions in which the planet will rise, transit and set for your selected latitude using the Rise/transit/set direction table. This also gives the angular altitude (angle above the horizon) that you will need to look for the planet when it reaches its highest point in your sky.

Examples of how to determine the rise, transit and set times of Mars using this procedure are given after the Rise/transit/set direction table.

Rise/Transit/Set Times Table

The table is colour-coded to reflect the sky conditions at the displayed time in each latitude:

Provided the sky is sufficiently dark, it is recommended that the observer waits about 30 minutes after the planet's rising time to allow the planet to reach a high enough altitude to clear the haze, turbulence and light pollution which is prevalent near the horizon - the latter being a particular problem in city and town locations. Likewise when setting, the observer should attempt to find the planet at least 30 minutes before its actual setting time. Be aware that, due to local sky conditions and an effect called atmospheric extinction (which causes celestial bodies to appear dimmer when they are close to the horizon), a planet or constellation may not be visible at all unless it is at least a few degrees above the horizon.

If Mars is some months away from opposition when it is observed, its coloration may not be immediately obvious to the naked eye; in which case, a pair of binoculars will help to reveal its trademark orange coloration.

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Rise/Transit/Set Directions Table

The directions in which Mars rises, transits and sets depends upon the constellation in which Mars appears at the time, and also on the observer's latitude. To find the rising/transiting/setting direction of Mars for your own location, refer to the following table and look up the directions for the nearest appropriate latitude:

We will demonstrate the above procedure with two examples - one for the Northern hemisphere and one for the Southern:

Example 1: Northern Hemisphere

My observing location is Austin, Texas (USA). At what time and in which direction will Mars rise, transit and set on October 25th, 2007?

> Austin is located at geographical latitude 30º 20' North, 97º 45' West. The nearest whole degree values are longitude 30º North (rounded down) and 98º West (rounded up); hence we will need to use the Latitude 30º North column in the Rise/transit/set times table.

Looking down the Date column, we see that, on October 25th 2007, Mars transits the meridian at 04:29 Local Mean Time, rises at 21:28 LMT (on the previous day) and sets at 11:30 LMT. Referring to the suffix notes (*) we see that DST applies in the USA during this time, so we must ADD ONE HOUR to our times to obtain our actual clock times. Hence the times now become 05:29 DST (transit), 22:28 DST (rise) and 12:30 DST (set). We can also see from the table that on October 25th, Mars rises in darkness (black background), transits in darkness and sets in daylight (light blue background).

We have determined that Mars transits the meridian at 05:29 DST. Now, this is the time at which Mars would appear on the meridian when seen from the central longitude of Austin's Time Zone (in this case, the Central Standard Time Zone, which is 6 hours behind GMT). The central longitude of the Central Standard Time Zone is (6 hours x 15º) = 90º West. The longitude of Austin itself (98º West) is 8º further West than its central Time Zone longitude (90º West). Referring to the page Finding the Local Standard Time (LST) from the Local Mean Time (LMT), we see that we must ADD FOUR MINUTES for each degree of longitude that we are positioned West of the central longitude. So we must add (8º x 4 minutes) = 32 minutes to all of the times we have noted down. Hence the local times of events at Austin are:

Having determined these times, we now need to know the directions in which we need to look to spot the planet at these times (in practice, we should wait about 30 minutes after the rising time - or observe at least 30 minutes before the setting time - to ensure that the planet is high enough to be visible). To find the directions, we refer to the Rise/transit/set direction table. We see that, at 30º North Latitude on October 25th, Mars rises in the ENE (East North-east) and sets in the WNW (West North-west). It transits the meridian due South, at an angular altitude of 82º ± 3 (i.e. between 79 and 85 degrees high).

Hence from Austin, Texas on October 25th 2007, we will see Mars rise in the ENE at 23:00 DST, cross the meridian (due South) seven hours later at 06:01 DST (at an altitude of about 82º) and set in the WNW a further seven hours later at 13:02 DST (by which time the Sun will be high in the sky).

• The software Redshift 5 gives the rising time of Mars at Austin on October 25th 2007 (using latitude 30º 20' North, longitude 97º 45' West) as 22:57 (Local Time), the transiting time as 05:59 (LT) and the setting time as 13:01 (LT). These are all within 3 minutes of our calculations, which is reasonably good considering that the calculations were performed on latitude and longitude values which were rounded to the nearest whole degree. However, we may expect the errors to be considerably greater than this in many instances, particularly where the observer's latitude is a few degrees or more to the North or South of those given in the table.

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Example 2: Southern Hemisphere

My observing location is Melbourne, Victoria (Australia). At what time and in which direction will Mars rise, transit and set on December 15th, 2007?

> Melbourne is located at geographical latitude 37º 40' South, 145º 0' East. In this case we will need to use the Latitude 35º South (Southern Australia) column in the Rise/transit/set times table. The longitude is precisely 145º, so no rounding up or down is necessary.

Looking down the Date column, we see that there is no entry for December 15th 2007, but we can estimate the times on December 15th by interpolating the times given on the dates on either side, i.e. December 9th and December 16th. There are (16 - 9) = 7 days between these two dates, during which interval the transit time of Mars changes from 01:28 (Local Mean Time) on December 9th to 00:49 (LMT) on December 16th, i.e. it transits earlier by (01:28 - 00:49) = 39 minutes in the space of 7 days, or about (39 minutes / 7 days) = 5.5 minutes per day (which we will round down to 5 minutes). Since there is only one day's difference between the listed date (December 16th) and our required observation date (December 15th) and we know that the transit times are getting earlier each day, we need to add 5 minutes to the transit time on the later date (December 16th) to get a transit time of (00:49 + 00:05) = 00:54 (LMT) on December 15th [Alternatively, we could have deducted (5.5 minutes x 6 days) = 33 minutes from the transit time on December 9th, which would have given us (01:28 - 00:33) = 00:55 (LMT). Either method of determining the time is acceptable; the difference of just one minute between the two methods is - for this purpose - negligible].

The method should now be repeated (by interpolation) for the rising and setting times of Mars (under the Latitude 35º South column). However, in most cases, the daily change of rise, transit and set times (i.e. minutes per day) will be roughly the same across all three events. Hence in this instance (and to make calculations easier) we can assume that the rising and setting times of Mars will also change by about 5 minutes per day. Hence, taking the rise and set times on December 16th as our basis, the rising time on December 15th is then (20:08 + 00:05) = 20:13 (LMT) and the setting time is (05:30 + 00:05) = 05:35 (LMT).

We now refer to the suffix notes (^†) and we see that DST applies in Southern Australia during this time, so we must ADD ONE HOUR to our times to obtain our actual clock times. Hence the times now become 01:55 DST (transit), 21:13 DST (rise) and 06:35 DST (set). We can also see from the table that on December 16th - just one day ahead of our required observing date - Mars rises in twilight (dark blue background), transits in darkness and sets in daylight (light blue background). Since twilight is encroaching on the planet's visibility when rising on December 16th, we can assume it will already be having some effect on the planet's visibility when rising on our required date, which is just one day earlier.

We have determined that Mars transits the meridian at 01:55 DST. Now, this is the time at which Mars would appear on the meridian when seen from the central longitude of Melbourne's Time Zone (in this case, the Australian Eastern Standard Time Zone, which is 10 hours ahead of GMT). The central longitude of the Australian Eastern Standard Time Zone is (10 hours x 15º) = 150º East. The longitude of Melbourne itself (145º East) is 5º to the West of its central Time Zone longitude (150º East). Referring to the page Finding the Local Standard Time (LST) from the Local Mean Time (LMT), we see that we must ADD FOUR MINUTES for each degree of longitude that we are positioned West of the central longitude. So we must add (5º x 4 minutes) = 20 minutes to all of the times we have noted down. Hence the local times of events at Melbourne are:

Now we need to know the directions in which we need to look to look for the planet at these times (in practice, we should wait about 30 minutes after the rising time - or observe at least 30 minutes before the setting time - to ensure that the planet is high enough to be visible). To find the directions, we refer to the Rise/transit/set direction table. We see that, at 35º South latitude on December 15th, Mars rises in the ENE (East North-east) and sets in the WNW (West North-west). It transits the meridian due North, at an angular altitude of 63º ± 3 (i.e. between 60 and 66 degrees high).

Hence from Melbourne, Australia on December 15th, we will see Mars rise in twilight in the ENE at 21:33 DST, cross the meridian (due North) just under five hours later at 02:15 DST (at an altitude of about 63º) and set in the WNW a further five hours later at 06:55 DST (by which time the Sun will have risen).

• The software Redshift 5 gives the rising time of Mars at Melbourne on December 15th 2007 (using latitude 37º 40' South, longitude 145º 0' East) as 21:44 (Local Time), the transiting time as 02:17 (LT) and the setting time as 06:50 (LT). Our calculated rising time is 11 minutes in error; the other two are within 5 minutes of our calculations, which gives some idea of the kind of error we can expect where the observer's latitude is situated a few degrees away from those given in the table.

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Credits

• The rising, transit and setting times of Mars were obtained from RedShift 5. Sky colorations were determined using the software's 'True Sky Color' feature.

Copyright  Martin J Powell  November 2006