As humans, we intuitively tend to interpret the things we see in our local time frame. However, the rate at which time flows at any point (or time) in the Universe is affected by the strength of the gravitational field at that point (or time). Hence when we see distant events through our telescopes and interpret them in the lab in our own time frame (time rate), errors will occur. Nearly all the methods of measuring a star’s tangential velocity involve taking a number of measurements at known increments of time. (Red-shifting only measures radial velocity). The increment of time is measured in earth time units since it is difficult to remotely calculate the star’s time frame Hence we are always viewing the velocity of the star in the time frame of the earth. This will produce velocities which appear higher than the actual local velocities when viewing a star with mass greater than the earth. This is a type of time blindness. For example, the stars close to the Black Hole at the centre of the Milky Way are observed to be moving faster than predicted by classical theory To explain this, Dark matter has been “invented” to explain the higher than expected gravitational force necessary to produce these higher velocities. However, time in the extreme gravitational fields close to a black hole is known to slow down. So, are these stars actually moving at this unusual speed or is the difference in time frame making it appear to us that they are moving faster than they should be? If we can explain the observed anomalies in velocity by the difference in time frames between the star and the earth, do we still need Dark Matter? More worryingly, if time frame difference is not routinely corrected for, are we looking at a distorted picture of the Universe? The size of the error could potentially be very large. For example, the time rate close to a black hole is thought to approach zero and hence the corresponding velocity in our time frame would approach infinity. The data comparing actual speeds (measured in our time frame) of stars close to black holes with the speeds calculated from Newtonian theory could be used to calculate how much of the error is caused by changes in time frame. Time Rate Mapping A very useful tool would be if time frames could be mapped. The ratio of local time rate to GMT time rate could be used as a parameter. This could be done from gravitational lensing and by observing the speed of rotation of stars round black holes and galaxies round clumps of galaxies. This is similar to the methods used to map dark matter. This combined with the fact that dark matter appears to attract galaxies, which are areas of high gravity and slow time, could mean that a slow time map would be very similar to a dark matter map. It might even be possible to use existing dark matter maps to produce an approximate time correction when measuring the tangential velocity of stars.