Institute of Astronomy

Undergraduate Study at the Institute of Astronomy

The Choice: Part II Astrophysics or Part II + Part III Astrophysics?

Students usually enter Part II Astrophysics on completion of Part IB in either Mathematics or Physics. Those going on to Part III Astrophysics have normally taken Part II Astrophysics. There is a possibility of changing to Part III Astrophysics from Part II Mathematics or Part II Physics. There is no restriction on entry for Part II Astrophysics, but the number of Part III places is limited by the number of potential projects (and project supervisors) available. Preference is given to students who have taken Part II Astrophysics.

It is not necessary for students to decide on whether to apply to go on to take Part III Astrophysics at the time they begin the Part II course.  In order to be a candidate for honours in Astrophysics in Part III of the Natural Sciences Tripos, a student should have obtained at least a II.1 in Astrophysics or Physics in Part II of the Natural Sciences Tripos.  Part II Mathematics Tripos students should have obtained at least a II.1 and will be considered on a case-by-case basis because it is required that they should have demonstrated a good grasp of at least three appropriate applied mathematics courses in the examination.

All students who proceed to Part III Astrophysics are generally required to complete at least one of the CATAM computer projects organized by the Mathematics Faculty. The computer project work may either be taken for examination credit during the year (in lieu of the extended essay) or, alternatively, completed during the long vacation following completion of Part II. A grade of at least a Beta for the project is required for admission to the Part III course.

Part II Astrophysics: Course Content

The syllabus includes eight lecture courses split between the Michaelmas and Lent terms. These lecture courses come in two flavours: those which teach the fundamental physics underlying the rest of the course and those which apply these concepts to particular astronomical subject areas.

This year there were four courses in the Michaelmas Term, two on essential physics, Principles of Quantum Mechanics (taught in the Mathematics Department) and Relativity (in the Physics department) plus two courses in astrophysics, Structure and Evolution of Stars and Stellar Dynamics and Structure of Galaxies (both at the IoA). There are four further courses in the Lent term. Topics in Astrophysics plays the dual role of introducing students to a range of exciting topics in contemporary astrophysics, while developing abilities in physical reasoning and order of magnitude estimates in an astronomical context. Statistical Physics (in Mathematics) and Astrophysical Fluid Dynamics (in the Physics department) continue the essential physics education and Introduction to Cosmology (at the IoA) adds a further course.

The style throughout requires minimal memorizing of descriptive terminology, and avoids the simple quoting and application of complicated formulae. Rather, lecturers will concentrate on the derivations of fundamentals from first principles, and the teaching of basic understanding.

There is also an examinable coursework component (comprising about 1/8 of the marks) for which students have two options: an extended essay (selected from a list of titles on contemporary research issues, announced in the Michaelmas term) or else the completion of typically two of the CATAM computer projects organized by the Mathematics Faculty, and which include astrophysical options. The projects are aimed at enabling students with a research career in mind to develop the necessary ability to solve various problems by numerical means. Note that although students may freely choose which option to take, any students proceeding to Part III Astrophysics will be required to demonstrate the necessary computing skills, normally by completing at least one CATAM computing project, before commencing Part III; thus any such students who chose the essay as examinable work will need to complete a CATAM project over the summer.

For further details please see the Part II Astrophysics Course Guide, (2022/2023).

Part III Astrophysics

This course leads to a MSci. degree and is mainly intended as preparation for graduate studies in astrophysics, although the high level of mathematical rigour means that graduates are also highly attractive to employers in other sectors. Lecture courses are taken mainly from the wide selection of astrophysics courses taught, often by Institute of Astronomy staff, as part of the Part III Mathematics and from two courses offered in Part III Physics. Students normally take four lecture courses for examination although they often attend a wider range of lectures for interest.

Although most of those taking Part III Astrophysics will have taken Part II Astrophysics, the fact that most Part III Astrophysics and Part III Mathematics lectures (and examinations) are the same, means that for interested Part II Mathematics students, of sufficient standard, Part III Astrophysics is an alternative to Part III Mathematics. The main difference is that Part III Astrophysics students take one less lecture course (and examination), but undertake a more substantial project, instead of the Essay. It is also possible in principle, for mathematically able students who have taken Part II Physics to take Part III Astrophysics (at the discretion of their Director of Studies and of the IoA), provided they have taken the Lent Term option in Astrophysical Fluid Dynamics. Students contemplating the route from either Part II Maths or Part II Physics into Part III Astrophysics should be aware that, in the case of over-subscription, priority will be given to suitably qualified students who have done Part II Astrophysics.

Astrophysics courses currently offered in Part III Mathematics (these change from year to year) include Astrophysical Fluid Dynamics, Structure and Evolution of Stars, Formation of Galaxies, General Relativity, Black Holes, Cosmology, Extrasolar Planets and Modern Stellar Dynamics.

Further details of the courses may be found at the Faculty of Mathematics. Examinations are the same as those taken by students taking Part III Mathematics.

Part III Astrophysics students may also offer the Part III Physics courses Physics of the Earth as a Planet, Relativistic Astrophysics and Cosmology or Particle Physics. Further details of the courses may be found at the Department of Physics. Examinations are the same as those taken by students taking Part III Physics.

A major component of the Part III Astrophysics course is the research project (accounting for one third of the marks) which is supervised by staff at the IoA over the Michaelmas and Lent Terms. This provides undergraduates with a unique opportunity to get to the cutting edge of astronomical research and the resulting dissertation often contains work of publishable quality. Projects often either involve the analysis of astronomical data or the running of computer simulations. In addition, students develop their communication skills through giving an oral presentation on their project.

All Part II students who proceed to Part III Astrophysics, who offered an extended essay for examination in lieu of computer projects organized by the Mathematical Faculty, must submit (in the September prior to commencing Part III Astrophysics) a project of at least 8 units from a selection provided by the IoA CATAM advisor. This year's question can be found on the CATAM webpage.

For further details please see the Part III Astrophysics Course Guide (2022/2023).

Frequently Asked Questions

How mathematical is the Part II Astrophysics course - would the average physicist cope?

The Part II Astrophysics course is somewhat more mathematical than Part II Physics and thus may involve some adjustment by students from a physics background during the first term of the course. Nevertheless we find that some of our most mathematically rigorous courses are among the most popular and successful courses for students from all backgrounds.

Mathematicians and physicists entering Part II Astrophysics have different skills and have done different courses in Part IB - so how does this work?

Both mathematicians and physicists will meet both familiar and unfamiliar material. For example mathematicians may be familiar with some of the topics covered in the Astrophysical Fluid Dynamics course and physicists will likewise have met some material in the Statistical Physics course. The differences in approach of mathematics and physics students are addressed in supervisions: physicists learn greater confidence with mathematics whilst mathematicians are encouraged to develop more physically intuitive ways of looking at problems. In practice, the differences between former mathematicians and former Natural Scientists are much less pronounced by the end of the year.

Will I learn less fundamental physics than in Part II/Part III physics?

The key thing here is that you will learn different physics (with some overlap, of course) with the physics emphasised being that which is most relevant to astronomical rather than terrestrial contexts. Thus you'll learn considerably more dynamics but considerably less about solid state physics than in the physics course.

Do I restrict my options by doing Part II Astrophysics?

Inevitably, yes: any specialisation closes some doors and opens others. In practice this means that any student contemplating postgraduate research in another branch of physics (such as condensed matter) should remain in the Physics Tripos.

Are there any practicals or opportunities to use telescopes?

There is currently no practical component of the course, although we review this issue regularly in consultation with the students. The IoA however houses a number of telescopes, including the historic Northumberland and Thorrowgood telescopes, and students are encouraged to join CUAS, who provide training in the use of these telescopes as well as organising a programme of entertaining astronomical lectures.

How difficult is the Part II course?

Part II Astrophysics should not be regarded as a soft option and it is found to be challenging to mathematicians and physicists alike. On the other hand, students on average advance a class in Tripos between their Part I and Part II Astrophysics result, suggesting that the majority of students rise to this challenge. More dramatic changes in class (e.g. III -> I) are not unknown, as students are inspired by the course content and rediscover their scientific curiosity. Due to the small class size, exams are not marked to conform to a standard mark distribution which therefore varies greatly from year to year according to the enthusiasms and abilities of the student cohort.

How difficult is the Part III course?

The taught component of Part III Astrophysics derives from Part III Maths and so one should not underestimate the pace and mathematical rigour of the course. On the other hand, our selection procedure for this course means that the students who go on to Part III Astrophysics appear to be well equipped for the course, judging by their Part III results (to date the great majority have obtained 2.1s and Firsts).

Can I study astrophysics within the Mathematics and Physics Triposes?

The answer is yes in both cases. For mathematicians there are two Part II courses covering astrophysical topics (Cosmology and General Relativity), with the wide range of topics at the Part III level. Physicists take a Relativity course in the Michaelmas Term and can opt to take the IoA's Astrophysical Fluid Dynamics course as a Lent Term option (both these courses being shared with Part II Astrophysics). In Part III Physics, students may take a major option and some minor options in Part III that are astronomically related, as well as having the opportunity to do some astronomically related project work, although this is less extended than the project work component of Part III Astrophysics. The breadth and depth of astrophysical courses offered in Part III Physics is in general less than in Part III Astrophysics (or Mathematics), but, as a trade-off, students obtain a better grounding in non-astronomically related physics at the Part II level.

Can I make non-standard transitions between Mathematics and Astrophysics and Physics at the Part III level?

Maybe, but this is a matter for discussion with your Director of Studies and the departments involved. In general, transitions between Mathematics and Astrophysics at the Part II to Part III level are straightforward in either direction for qualified students. Transfers between Physics and Astrophysics after three years are now possible for suitably qualified students who have taken the Astrophysical Fluid Dynamics option in the Lent Term of Part II Physics. In addition, such students will be expected to complete a CATAM computing project over the summer. Those wishing to transfer into Astrophysics at the Part III level should note that, in the case of over-subscription, priority will be given to those coming from Part II Astrophysics. Transfers between Part II Astrophysics and Part III Physics are not encouraged.

What do people do after Part II and Part III Astrophysics?

The destinations of Astrophysics graduates after Cambridge are very varied. Many have proceeded to PhDs in astronomy; in recent years, most of our students taking this path have taken the Part III Astrophysics course, which is regarded as an elite qualification by astronomy departments both in Cambridge and elsewhere in the UK. A number of students have also gone on to acquire a range of (non astronomy related) further qualifications that build on the solid mathematical skills acquired in Part II Astrophysics.  Astrophysics degrees also equip graduates for a range of non academic jobs, including teaching, software development, financial services and accountancy. Our graduates include investment bankers, business analysts, workers in the media and a vicar. In the words of an alumnus from 1996/1997 "...having 'Astrophysics Cambridge' on one's CV certainly opens a lot of doors!"


We end with some quotes made by our Part II students over the last decade, which we selected from many in a similarly enthusiastic vein:

"The course was fantastic and more than lived up to my expectations, and the IoA is a really cool place" .

" ...Though hard at times, I'm very glad I chose to study this as my third year option and have really enjoyed the course content and also the atmosphere of the department: the friendliness and relaxed atmosphere have made it even more enjoyable"

"I think I cannot praise it much higher than to say that if the rest of my time at Cambridge had been like this year then I might not be leaving. I think the course is a credit to the people involved with it...I have enjoyed it and had my interest re-ignited, something I feared had been killed off for good"

" doing a PhD in Astrophysics. The Institute provided me with the academic background I needed. It also provided me with great inspiration and motivation"

"Very enjoyable, challenging but manageable thanks to the support of the staff and lecturers. The environment is really nice at the department and I would definitely recommend the course in the future!"

...and on Part III

"Department is great. Very welcoming. Completely comprehensive access to facilities. Often attended seminars and colloquia. The staff are all very approachable and keen to help if they can"

"I think the IoA staff and facilities are amazing. It was very easy to see people and I really felt welcomed into the department. It is a lovely environment to work in and if anything was going to convince me into further study it would have been the people and atmosphere at the IoA."

"I have had a wonderful year and thoroughly enjoyed the course."

"A very enjoyable course and well-organised."

"Really nice course ... My most enjoyable year from works point of view."

How to Apply

Part IB to Part II Astrophysics

Students wishing to enrol for Part II Astrophysics only need obtain the agreement of their Director of Studies. It is helpful, however, for the Institute of Astronomy to know of your intention to take the course by the end of the previous Easter term so we can keep you informed of introductory lectures and arrange supervisions in good time.

Part II to Part III Astrophysics

Those taking Part II Mathematics or Part II Physics who are interested in taking Part III Astrophysics in their 4th year should contact the Institute of Astronomy as early as possible (preferably no later than the end of the previous Easter term) to ascertain the likelihood of places being available. This is subject to obtaining a II.1 in Part II. In either case, please email

More information on expected course prerequisites for Part II and Part III Astrophysics, can be found here.

Any requests for further information should be directed to Professor Chris Tout ( or to the undergraduate adminstrator

Prerequisites for PartII_PartIIIAstro.pdf65.26 KB
2022 -23 Pt III MASt Course Guide.pdf738.47 KB
2022-23 Part II Astrophysics Course Guide.pdf997.29 KB
Open Day Talks 28.02.23204.89 MB
2023-24 Brochure4.23 MB
Page last updated: 7 March 2023 at 09:43